Darlington Labs MM-5 Review (Phono Stage)

[drmevo]

We're not planning on a series of odd-numbered models.
We do have an MP-8 in our product roadmap which will likely be 5 to 6X the price of the MP-7, using tubes as well as high-voltage J-FETs. It will be targeted at cost-no-object systems.

While the conventional specifications of the MP-8 may be superior (especially via the tube-balanced-output), they are unlikely to be "too far to the left" on Amir's graphs of THD/SINAD performance. We use our ears and eyes in the design process. The marketplace has many high-feedback designs that measure well on the basic ASR methodology.

The MP-7 has proven to be our best seller of all three current models based on client interest and feedback. Many clients remark that it is an "end-stage" preamp, meaning they have stopped looking for an upgrade and are simply enjoying their music.

To us, that means far more than output from an Audio Precision interface, even though we have previously attempted to describe why we believe that our measured results are indeed actually more consistent with the true perceptive envelope of the human ear than many other marketplace options. A blind A/B test through an audio interface, or even a high-end 30-IPS tape machine is probably not going to solve that debate.

As an owner of an MM-5, I look forward to trying an MP-7 one day. I have to say, it's too bad none of your responses in this thread lead to responses from Amir. I'm sure he is a very busy guy but I don't imagine it is all that often that the designer of equipment that gets reviewed here comes to participate in the review thread. I'd be interested to hear why, after your seemingly thorough explanations (rebuttals, if one wants to be blunt), the MM-5 is still not recommended, but in all honestly it matters not to me. According to this site, the original Schiit Mani should be better, but I can't imagine someone hearing both phono amps in my system and saying they prefer the Mani. I guess that shows how much value the phono stage reviews have, in my eyes.

 

[krichard2496]

As an owner of an MM-5, I look forward to trying an MP-7 one day. I have to say, it's too bad none of your responses in this thread lead to responses from Amir. I'm sure he is a very busy guy but I don't imagine it is all that often that the designer of equipment that gets reviewed here comes to participate in the review thread. I'd be interested to hear why, after your seemingly thorough explanations (rebuttals, if one wants to be blunt), the MM-5 is still not recommended, but in all honestly it matters not to me. According to this site, the original Schiit Mani should be better, but I can't imagine someone hearing both phono amps in my system and saying they prefer the Mani. I guess that shows how much value the phono stage reviews have, in my eyes.

We are contemplating an entry-level unit below the MM-5 that would indeed be a feedback design (J-FET input), high power supply rail, regenerated internally, very unique, and would probably be acceptable to Amir in terms of aurally-unweighted THD.

I think having a product line with a 1:33 price ratio would be quite the statement. Especially if the much lower-end one receives a superior review via his methodology.

 

[mike70]

To us, that means far more than output from an Audio Precision interface, even though we have previously attempted to describe why we believe that our measured results are indeed actually more consistent with the true perceptive envelope of the human ear than many other marketplace options. A blind A/B test through an audio interface, or even a high-end 30-IPS tape machine is probably not going to solve that debate

I respect your opinion / decisions ... but in my opinion ... I wouldn't buy the improved version if an Audio Precision device can't find any improvement. Magic can't made better audio devices.

So ... you can do the best of both worlds, sell to people that hear improvements and trust in their brains ... and also presenting a more rational difference through quality digital files to the "sceptical people"

 

[Yaroha]

Jason Victor Serinus, is that you?

No I have a different name, if not a secret why do you ask?

 

[krichard2496]

No I have a different name, if not a secret why do you ask?

My impression is that he was trying to poke fun of your very nice descriptions of sound quality by connoting you with the Stereophile reviewer of that name.

I don't know Jason but I would hope he agrees that this sounds quite good on the double-vinyl LP:

Speaking of 1989, if you were to crack open a stereo mag from that year (the last issue of High Fidelity, RIP, or AUDIO, RIP, or Stereo Review and the great Julian Hirsch, or possibly even some Stereophile (the small-format ones) like Peter W. Mitchell, you would be met with "need to buy your last stylus, vinyl is dead, dead, dead."

And paraphrasing Phil Collins, against all odds, I'd say the marketplace has spoken.

 

[Digital1955]

We are contemplating an entry-level unit below the MM-5 that would indeed be a feedback design (J-FET input), high power supply rail, regenerated internally, very unique, and would probably be acceptable to Amir in terms of aurally-unweighted THD.

I think having a product line with a 1:33 price ratio would be quite the statement. Especially if the much lower-end one receives a superior review via his methodology.

I understand that from a marketing perspective that you want to "slam dunk" Amir's chart. But it seems to run counter to your company's entire philosophy and what you have been saying here, that "feedback isn't ideal" (paraphrasing). Can you suggest some new test that Amir could perform to demonstrate the sonic differences that you have been documenting on your company's webpage? For example, Amir has solicited feedback before on a transient test:

Schiit Mani 2 Review (Phono Stage)

This is a review and detailed measurements of the Schiit Mani 2 phono preamplifier. It was sent to me by the company and costs US $149. Naturally the unit looks like other Schiit products and seems to even have the previous Mani skin given the lack of "2" designation in the front. Fortunately...

audiosciencereview.com

As you know, you will obviously never win this forum over by repeating that you do extensive listening tests and that way leads your designs. There is nothing at all wrong with that, except that you have designed something to your preferences, which may or not be useful or valuable to the end customer. Yes, I realize you have a trial, but so does virtually all others in some way or another (a large USA online dealer has a 60 day trial for anything they sell). There are so many phono stages in the market today - that it makes it hard for anybody to cut through all the marketing and have some objective way to understand if there are actually any differences between a 100$ unit and a 10000$ unit.

-Scott

 

[krichard2496]

I understand that from a marketing perspective that you want to "slam dunk" Amir's chart. But it seems to run counter to your company's entire philosophy and what you have been saying here, that "feedback isn't ideal" (paraphrasing). Can you suggest some new test that Amir could perform to demonstrate the sonic differences that you have been documenting on your company's webpage? For example, Amir has solicited feedback before on a transient test:

Schiit Mani 2 Review (Phono Stage)

This is a review and detailed measurements of the Schiit Mani 2 phono preamplifier. It was sent to me by the company and costs US $149. Naturally the unit looks like other Schiit products and seems to even have the previous Mani skin given the lack of "2" designation in the front. Fortunately...

audiosciencereview.com

As you know, you will obviously never win this forum over by repeating that you do extensive listening tests and that way leads your designs. There is nothing at all wrong with that, except that you have designed something to your preferences, which may or not be useful or valuable to the end customer. Yes, I realize you have a trial, but so does virtually all others in some way or another (a large USA online dealer has a 60 day trial for anything they sell). There are so many phono stages in the market today - that it makes it hard for anybody to cut through all the marketing and have some objective way to understand if there are actually any differences between a 100$ unit and a 10000$ unit.

-Scott

We suggest again that Amir incorporate D.E.L. Shorter's October 1949 methodology wherein each higher harmonic is weighted at N to the 4th power. We have heard no refutation of what I would call an "honest broker/engineer" i.e. a member of BBC staff who was clearly an experienced listener, and an experienced scientist, and who did not have an "axe to grind". His research paper, available today on the BBC research website, mentions a 1937 RMA standard of a directionally-similar nature which had not yet gained much traction in 1949. One can imagine the makers of pentode-output radios wouldn't have supported it.

These debates aren't at all new.

The reason that we would consider an entry level, all-discrete, feedback product is my view that the entire low-end of the available marketplace is awash with recycled and stale ideas running on 18VDC or less. Our view is that from a sonic perspective, most listeners would be better off streaming high-resolution digital files rather than playing vinyl with a competitor's sub-$150 preamp. It would be a marketing gamble, to say, "listen to what we can do with $89" for potential buyers who do not wish to avail themselves of our money-back return policy on higher end units. Developing (non-US/Europe) markets also have different price needs and a large gap between USD $25, $149 and $1000 units.

We might credit the purchase price of a entry-level unit like that against the purchase of an MM-6 or better in the lineup, and the user could then employ said model on a second or third turntable setup, or give it to a family member or friend who needs a sonic upgrade. At the price point we are talking about, it is not practical to produce a product using our 5-inch aluminum chassis, nor to be able to incorporate significant "hand-fine-tuning". A small plastic chassis with a ground-plane double-sided PCB would benefit from the inherent EMI rejection of a feedback topology. We would not produce it with the idea of "gaming an ASR test". I was commenting that a counter-intutive review acceptance of a low-end product would still be worth noting.

 

[teched58]

We suggest again that Amir incorporate D.E.L. Shorter's October 1949 methodology wherein each higher harmonic is weighted at N to the 4th power. We have heard no refutation of what I would call an "honest broker/engineer" i.e. a member of BBC staff who was clearly an experienced listener, and an experienced scientist, and who did not have an "axe to grind" ie was a producer of integrated circuit/high-feedback products in the marketplace.

The reason that we would consider an entry level, all-discrete, feedback product is my view that the entire low-end of the available marketplace is awash with recycled stale ideas running on 18VDC or less. Our view is that from a sonic perspective, most listeners would be better off streaming high-resolution digital files rather than playing vinyl with a competitor's sub-$150 preamp. It would be a marketing gamble, to say, "listen to what we can do with $89" for potential buyers who do not wish to avail themselves of our money-back return policy on higher end units.

We might credit the purchase price of a low-end unit like that against the purchase of an MM-6 or better in the lineup, and the user could then employ our entry level model on a second or third turntable setup, or give it to a child or friend who needs a sonic upgrade.

At the price point we are talking about, it is not practical to produce a produce with our 5 inch alumium chassis, nor to be able to incorporate much "hand-fine-tuning". That is why it would be a feedback design. Although I have thought strongly about making an Amir-Approved MM-5 with a differential output stage, and having him test it for his "low THD" stamp of approval. Most people wouldn't notice too big of sonic detriment if they actually listened to it. I have also thought of an internal DIP setting "Test/Operate" which is what broadcast audio processors have. But all of that is messy and hard to explain in the marketplace.

As I've said before, feedback is only one way to achieve a low-non-aurally-weighted THD.

You are making this much, much, much too complicated. I take it you are an engineer by training; no marketing person would unknowingly work so hard to extract defeat from the jaws of victory.

YOU BASICALLY GOT A GOOD REVIEW. TAKE THE WIN.

If you have spent any significant time reading thru threads in the year since you joined, you would know that a) this review gives people who are ok w your feedback philosophy an "ok" to buy this product and b) people who do what you're doing eventually have Amir turn on them (look up Erin).

 

[krichard2496]

You are making this much, much, much too complicated. I take it you are an engineer by training; no marketing person would unknowingly work so hard to extract defeat from the jaws of victory.

YOU BASICALLY GOT A GOOD REVIEW. TAKE THE WIN.

If you have spent any significant time reading thru threads in the year since you joined, you would a) know that this review gives people who are ok w your feedback philosophy an "ok" to buy this product and b) people who do what you're doing eventually have Amir turn on them (look up Erin).

We have derived quite a bit of business from this forum.

We are NOT looking to have anyone "turn on/against" anyone. We hope that a hobby can be both fun and intellectually stimulating. It was another poster, not ourselves, that postulated about replies or refutations - not us. If you've purused the Audio History section of our website, which someone called "highly opinioned and a total gas", being frank about opinions is true to form for us. Yes, we are engineering-driven. I tend to agree with Bob Lutz's philosophy on bean-counters, Marketing and your typical MBA even though he himself was educated at UC Berkeley with an honorary Doctorate from Kettering, and I spent many years in corporate America before this venture. I also won't comment on or characterize the typical feedback we've received in-house from clients and potential clients about the ASR website.

Derivation and use of a steeply-weighted THD metric could potentially solve a myriad of disagreement and could move the industry forward. Amir seems to be in a unique position to do it.

The Vinyl LP Medium itself generates 5 to 12% conventional low-order THD...regardless of which preamp you use. Yet, the marketplace has decided that enough people like it to cause sales to generally increase year over year since the mid-1990s, and not all of that can be attributed to packaging or graphics advantages. (Fundamentally and critically, we believe that the sonic benefit is IN SPITE of that low order THD, not because of it. Splashing low-order THD via an "exciter-type" circuit on a contaminated signal might improve it somewhat, but we firmly believe other things are at play).

Many radio stations today are playing high-resolution needle-drops of original vinyl LP releases, even when there are many CD and digital reissues available.
Radio stations have Arbitron numbers that can provide them real-time visibility into cut-by-cut listening attention, and even with the declicking software used, there is still a modicum of surface noise present, just waiting to be grabbed by the multiband processors. Would they be going to the trouble if they weren't convinced it provided them an actual advantage in TSL (Time Spent Listening)?

Isn't that, "de facto", an argument to suggest that more advanced, hearing-based testing methodologies are required? To paraphrase that old Elvis greatest hits album, can 50,000,000 fans be wrong?

 

[Angsty]

I use the brush as well before playing the record. It do the job well but by the end of the first side it’s build up so much static on vinyl that I get more pops unless I use the brush again at the end of the record. I get better results if I use a bit of spray and wipe cleaner. Thank you for the advice I know there is a gun that can help with that but my previous turntable didn’t have as much static problem that’s why I was thinking it could be something that contributing to excessive static electricity

You might want to try an antistatic mat. I have an inexpensive Sleeve City mat on my VPI that works wonders in keeping static down. My Pioneer turntable with its rubber mat has terrible static by comparison.

 

[teched58]

We have derived quite a bit of business from this forum.

We are NOT looking to have anyone "turn on/against" anyone. We hope that a hobby can be both fun and intellectually stimulating. It was another poster, not ourselves, that postulated about replies or refutations - not us. If you've purused the Audio History section of our website, which someone called "highly opinioned and a total gas", being frank about opinions is true to form for us. Yes, we are engineering-driven. I tend to agree with Bob Lutz's philosophy on bean-counters, Marketing and your typical MBA even though he himself was educated at UC Berkeley with an honorary Doctorate from Kettering, and I spent many years in corporate America before this venture. I also won't comment on or characterize the typical feedback we've received in-house from clients and potential clients about the ASR website.

Derivation and use of a steeply-weighted THD metric could potentially solve a myriad of disagreement and could move the industry forward. Amir seems to be in a unique position to do it.

The Vinyl LP Medium itself generates 5 to 12% conventional low-order THD...regardless of which preamp you use. Yet, the marketplace has decided that enough people like it to cause sales to generally increase year over year since the mid-1990s, and not all of that can be attributed to packaging or graphics advantages. (Fundamentally and critically, we believe that the sonic benefit is IN SPITE of that low order THD, not because of it. Splashing low-order THD via an "exciter-type" circuit on a contaminated signal might improve it somewhat, but we firmly believe other things are at play).

Many radio stations today are playing high-resolution needle-drops of original vinyl LP releases, even when there are many CD and digital reissues available.
Radio stations have Arbitron numbers that can provide them real-time visibility into cut-by-cut listening attention, and even with the declicking software used, there is still a modicum of surface noise present, just waiting to be grabbed by the multiband processors. Would they be going to the trouble if they weren't convinced it provided them an actual advantage in TSL (Time Spent Listening)?

Isn't that, "de facto", an argument to suggest that more advanced, hearing-based testing methodologies are required? To paraphrase that old Elvis greatest hits album, can 50,000,000 fans be wrong?

Keith, I quoted your full post (in case it changes again, since you've been editing it so frequently), but what I really want to ask about is the somewhat cryptic line at the end of the second paragraph (which I put into bold in the quote above and below for visibility; i.e. the bold was mine, not yours). The sentence however is yours; it is this:

> "I also won't comment on or characterize the typical feedback we've received in-house from clients and potential clients about the ASR website."

Can you provide some more perspective on this? Most people here at ASR like and value this site. Is that what you're hearing from those clients and potential clients? Has ASR helped them make decisions on phono preamps?

 

[krichard2496]

Keith, I quoted your full post (in case it changes again, since you've been editing it so frequently), but what I really want to ask about is the somewhat cryptic line at the end of the second paragraph (which I put into bold in the quote above and below for visibility; i.e. the bold was mine, not yours). The sentence however is yours; it is this:

> "I also won't comment on or characterize the typical feedback we've received in-house from clients and potential clients about the ASR website."

Can you provide some more perspective on this? Most people here at ASR like and value this site. Is that what you're hearing from those clients and potential clients? Has ASR helped them make decisions on phono preamps?

Still won't comment.

Other forums often "lock down" editing after 30 minutes or so, not a bad idea to do here. We are trying hard to run a business that is the equivalent of "running a somewhat profitable airline while other people argue about whether the world is round or flat."

 

[Yaroha]

You might want to try an antistatic mat. I have an inexpensive Sleeve City mat on my VPI that works wonders in keeping static down. My Pioneer turntable with its rubber mat has terrible static by comparison.

Thank you for the info, I will try this mat and see if it makes the difference. So far I have tried cork mat by Music Hall and currently using Funk Firm mat.

 

[Billy Budapest]

Thank you Amir for the review.

The single-ended Class-A feedback-free gain circuitry is a conscious design choice.
We could have chosen differential-operation of the gain stages and still not used feedback; the result would be around -70dB to -80dB second harmonic distortion.

As it is, we could also 'optimise' the second harmonic and lower it a few dB by trading off some overload headroom. Doing so in our ear leads to a brightened, forward, more strident quality and increases the relative proportion of the third harmonic. Also note that unlike other units which also use Passive-RIAA EQ, our special design avoids an increase in High Frequency distortion due to overload of the input stage.

Third harmonic at ~ -103dB as tested is a goal which we worked hard to achieve. Lastly, unlike some other "no feedback" units, our models have a low-impedance output that interface well with most gear. The residual mains harmonics are NOT related to a noisy regulation scheme; they are induced due to the size of the enclosure, and with A-weighting being typical of the ear's response, are inaudible in normal conditions.

Our listening tests lead us to the current design.
We have a 30 day return option for all clients to audition the unit (or our other higher-end models) in their own system.

Sincerely,
Keith Richardson
Director of Engineering
Darlington Labs LLC

It seems to me that in the measurements that count (i.e., are audible), this phono stage has very good performance. When playing back vinyl, I care less about distortion and noise specs because any distortion introduced by the playback circuitry is going to pale in comparison to the *distortion and noise inherent in the playback medium.* I.E., vinyl just is not a high fidelity source, if you are talking about faithfulness to the master recording. RIAA accuracy (for accurate tonal reproduction) and overload headroom (for coping with “overs” caused by momentary loud clicks and pops) are what matters most. Here, the Darlington Labs phono stage does an admirable job.

 

[krichard2496]

It seems to me that in the measurements that count (i.e., are audible), this phono stage has very good performance. When playing back vinyl, I care less about distortion and noise specs because any distortion introduced by the playback circuitry is going to pale in comparison to the *distortion and noise inherent in the playback medium.* I.E., vinyl just is not a high fidelity source, if you are talking about faithfulness to the master recording. RIAA accuracy (for accurate tonal reproduction) and overload headroom (for coping with “overs” caused by momentary loud clicks and pops) are what matters most. Here, the Darlington Labs phono stage does an admirable job.

Thank you for the assessment.

We have come to realize that, in our view, our design is ideally suited to actually reducing the audible impact of surface noise without harming the music.

The slow, natural increase in second-harmonic THD from its very low levels at normal output, up to the clip point which is greater than +27dBu (17V RMS, 49V pk-pk) is a slightly-compressive transfer function that - while not designed as such - effectively acts as a zero-attack-time, zero-release time, zero-overshoot "soft peak limiter". The output stage characteristic that predominates Amir's measurement is combined with our special input stage which we believe has a virtually-ideal frequency-spectrum-vs-overload characteristic that additionally helps take a slight "edge" off of ticks and pops in conjunction with the output stage.

User feedback seems very clear on the above points.

This is versus a hypothetical phono preamp which is absolutely completely distortion-free, whose distortion spectrum would not change with level, that would simply "not exaggerate surface noise", as most feedback designs tend to do, even when not driven fully to "clipping". We have never had a complaint of "I hear distortion" or "it sounds colored" in our designs. In fact, in very rare (less than 1 to 2%) cases, some people have said "too transparent". In our view, their system exhibits a slight upper-midrange or treble distortion that is not being masked, by virtue of the inherent clarity in our products. Also, new production MP-7s and MM-6s now use a triple-regulated power supply; to our knowledge, a first in any reasonably-priced product.

Our new low-noise, J-FET-input Moving Coil Step-Up / Head Amp series (the SU-7, SU-6 and SU-5) do use "some" feedback as we have found it necessary to maintain a low noise floor while controlling the gain. They would measure quite well in Amir's testing. Moreover, they feature more than 60dB (sixty decibels) of overload headroom, such that in all cases, the +40dB stage (MP-7, MM-6, or MM-5) overload characteristic will dominate, as described above.

In other words, the assessment of "In addition to great sound, Darlington Labs tends to minimize the audibility of surface noise" is true even with a Moving Coil cartridge in the context of an all-Darlington setup.

If you are coming to AXPONA next week, please drop by our booth (#9318 in the Expo Hall) to audition our technology for yourself.

 

[Billy Budapest]

I.E., vinyl just is not a high fidelity source, if you are talking about faithfulness to the master recording.

Let me clarify what I mean by this—the mechanics of vinyl playback including inner groove distortion, rumble, wow & flutter, the physics of what vinyl cutting and then stamping technology allows for such as limits on channel separation, dynamic range, and bass frequency reproduction, and then characteristics of the individual playback media itself, including dirt, wear, static electricity, non-fill, and all manner of surface noise no matter what the source—all add up to deviations from what was actually recorded on tape, and therefore compared to what is possible in digital reproduction and perhaps analog tape, vinyl is not a “high fidelity” medium. That doesn’t mean that it cannot sound good, but the limitations of vinyl introduce many audible artifacts that are far more significant than any noise or distortion introduced by the phono preamp.

 

[oldmanhifi]

I have been following the Amir's reviews of the phono preamps, as well as the comments of a number of members who seem to know a lot about phono preamp design. From those comments, it seems overload resistance and accurate RIAA compensation are very important. Some also believe that a subsonic high pass filter is important. After reviewing the test results of the MM-5 and the ensuing comments, Darlington Labs web page and design philosophy, and exchanging a couple of emails with Keith Richardson, I ordered a DL MM-6. I received it on Monday, 8-22 and it has been plugged in and turned on continuously since that time even when the rest of my system is off and I am not listening.

On first listen, I could tell it was a step up from my ifi Zen phono in terms of detail, but the bass and mids were not as awesome as I expected. After three days, that was no longer the case and during my listening session this morning I was really happy with the sound. As other reviewers (in other forums) have noted, it is full, coherent, with a wide and deep soundstage and never sounds like it is working hard or stressing. It is smooth without being syrupy, it is detailed without being "analytical." It just lets the music pour out and makes me want to put on another LP. I did have an issue with a small degree of 60 hz hum with a Goldring E3 cartridge, but when I put my Nagaoka MP-200 back on the Rega RB220 tonearm, that went away. And the MM-6 and MP-200 seem made for each other. My rig has never sounded so good.

I know this is a bunch of "subjectivist" opinion, but DL is offering pretty much a can't lose proposition: try it for 60 days and if you don't think it is worth the money, send it back for a refund. I know mine isn't going back. I think that the MM-6 is the classic case of champagne value on a beer budget.

 

[Bob from Florida]

I have been following the Amir's reviews of the phono preamps, as well as the comments of a number of members who seem to know a lot about phono preamp design. From those comments, it seems overload resistance and accurate RIAA compensation are very important. Some also believe that a subsonic high pass filter is important. After reviewing the test results of the MM-5 and the ensuing comments, Darlington Labs web page and design philosophy, and exchanging a couple of emails with Keith Richardson, I ordered a DL MM-6. I received it on Monday, 8-22 and it has been plugged in and turned on continuously since that time even when the rest of my system is off and I am not listening.

On first listen, I could tell it was a step up from my ifi Zen phono in terms of detail, but the bass and mids were not as awesome as I expected. After three days, that was no longer the case and during my listening session this morning I was really happy with the sound. As other reviewers (in other forums) have noted, it is full, coherent, with a wide and deep soundstage and never sounds like it is working hard or stressing. It is smooth without being syrupy, it is detailed without being "analytical." It just lets the music pour out and makes me want to put on another LP. I did have an issue with a small degree of 60 hz hum with a Goldring E3 cartridge, but when I put my Nagaoka MP-200 back on the Rega RB220 tonearm, that went away. And the MM-6 and MP-200 seem made for each other. My rig has never sounded so good.

I know this is a bunch of "subjectivist" opinion, but DL is offering pretty much a can't lose proposition: try it for 60 days and if you don't think it is worth the money, send it back for a refund. I know mine isn't going back. I think that the MM-6 is the classic case of champagne value on a beer budget.

Respectfully ask if you were able to match levels. Gains are different between the Zen and the MM-6. Might be worth swapping the Zen back in a time or two to verify.

 

[mike70]

You can digitize some track with both preamps, levels matched and compare it with foobar abx.

Then you tell me if you can recognize the mm-6 at least with 75% times ... and then I start to believe what you say.

 

[Digital1955]

You can digitize some track with both preamps, levels matched and compare it with foobar abx.

Then you tell me if you can recognize the mm-6 at least with 75% times ... and then I start to believe what you say.

How do you level match them if they don't have exactly the same frequency response? If you try taking some average, you will end up being able to still tell them apart. Even a small frequency response difference can be pretty audible. Better yet if you actually EQ one to match the other, then I bet you absolutely would not be able to tell them apart - unless one has some high pass or low pass filter and the other doesn't. FR, I am going to go out on a limb here on ASR, has by the far the largest impact on what we "hear" and "perceive". Assuming distortion levels are reasonably comparable as well (as in one doesn't have high levels of odd order harmonics).