Review and Measurements of Benchmark AHB2 Amp

[LTig]

now when your amp breaks you get to buy a new amp AND a new speaker

What about having the amp repaired?

 

[Martini]

What about having the amp repaired?

That may be less expensive, but it will certainly be less fun.

 

[RobS]

Has there been an amplifier made in the past 5 years at a similar price point (or less) that beats the Benchmark AHB2 in resolution?

I've had my AHB2 for the past four years and one of the things I am most appreciative of is its transparency; not just in extracting the finest detail in recordings but even down to exposing differences in cables, DACs, playback software etc. I would love to be able to measure these audible differences when switching upstream components to confirm what I'm hearing but I do not have proper measuring equipment. (With the AHB2, it's obvious when a certain recording played thru my chain with DAC "A" doesn't extract the level of detail that DAC "B" can. That is to say there's more detail in the recording that I am missing with a different DAC. It's not noise from either DAC. But this is an entirely different discussion...)

I do not like when other power amplifiers muddy, smear, omit things that are embedded in the recordings. I want all the warts, flaws, "things we weren't supposed to hear" presented. If the recording sucks, I want it to suck. Don't add goo, warmth, distortion, etc to make it better than it is. And that goes for extremely good recordings, I want to squeeze every detail out of them so they shine. With some recordings, you almost get an idea of how engineers made them. I just want my components to lift every possible veil; so if a flawed old recording I like so much is revealed to have even more flaws and issues, that's desirable to me. It's an enlightening experience as a listener. Resolution is my top priority when it comes to audio reproduction for serious critical listening, I want nothing sacrificed nor added.

Anyway I'm curious if there's been an amp that has bested the AHB2 in this area, at its price point. I've been out of buying various audio equipment for years but wanted to check on the current state of things. Also another thing that I really like about Benchmark is their commitment to their products having the lowest possible noise. It makes a positive difference when one is after high resolution.

 

[antcollinet]

Has there been an amplifier made in the past 5 years at a similar price point (or less) that beats the Benchmark AHB2 in resolution?

Well you'd have to define what you mean by resolution for an amplifier - in terms of normal amplifier metrics.

The closest metric to resolution would be be noise in terms of dynamic range. This can be equated to an "equivalent number of bits" (ENOB)

The benchmark (according to Amir's measurement achieves about 113dB at 5W (ENOB = almost 19 bits)


Looking at the best of the rest, we could compare with the Topping LA90, and the Hypex Nilai.

The topping smashes the Benchmark at 125dB (low gain) ENOB = almost 21 bits. However it doesn't deliver anywhere near the power of the benchmark. And it's...well... Topping

The Hypex Nilai based amp matches the Benchmark at 113dB (5W), and exceeds the power capability of the benchmark. It also matches the Benchmark in most other measures (especially distortion) again with that power benefit.

So, yes. I'd say there are other amps that match or beat the benchmark, at significantly lower price.


Having said that - in a properly controlled blind test, and operating within power limits I would be confident that no-one could tell the difference between these three amps - or indeed many others in the "Excellent" or even "very good" range of the Sinad chart.


EDIT - Look out for the purify 1ET9040BA based amps. I've not yet seen independent measurements, but I'm expect these to be beating both the Benchmark and Nilai at even higher powers.

 

[TheWalkman]

Rob:

For years, Benchmark held the standard for just how clean an amp could be, but at $3500 (+/-), I can get a Topping, Hypex, or in my case, a Purifi amp that is, for all intents and purposes, just as good for a fraction of the price.

I’ll admit, three or four years ago, I had a small degree of lust in my heart when I read about Benchmarks. Though I can afford a Benchmark, I could not rationalize/ justify spending that much money on an amp. (To be honest, with aging ears, my hearing has become the limiting link in my audio chain!)

Nearly two years ago, I justified purchasing a Purifi-based Audiophonics HP-S400 amp, and I can honestly say that I no longer have any interest in owning a Benchmark or any other new amp, for that matter.

The Audiophonics is an endgame purchase for me.

In addition— and this may not be quantifiable by me— I feel more confident in the long-term reliability of my Purifi amp compared to the Benchmark. Looking at the main circuit board of the Benchmark, it appears to me that with all of the discrete components, there are far more points of potential failure than with my simpler, module based Purifi amp. With three main boards in my amp, swapping a faulty module seems far simpler than trying to troubleshoot all the components on your Benchmark (though I’ll admit, long-term availability of Purifi modules would be the limiting factor).

(As I type this response, I’m listening to the news over my Purifi amp via a Sangean HD receiver. The broadcast sounds darned good to my ears - despite terrible new stories!)

That said, kudos to you for buying a Benchmark. It’s a great product.

To me, the magic of seeing the latest test results of a new amp review is gone. I own my holy grail amp.

I’m comfortable to admit that I don’t own the coolest amp. But even so, I am 100% satisfied with my purchase and until it one day emits magic, blue smoke, I won’t be lusting over amps any longer.

Cheers

 

[TheWalkman]

To clarify my point about complexity, I thought I’d add some pics of my Purifi amp compared to the Benchmark’s innards.

 

[Sal1950]

I've had my AHB2 for the past four years and one of the things I am most appreciative of is its transparency; not just in extracting the finest detail in recordings but even down to exposing differences in cables, DACs, playback software etc. I would love to be able to measure these audible differences when switching upstream components to confirm what I'm hearing but I do not have proper measuring equipment. (With the AHB2, it's obvious when a certain recording played thru my chain with DAC "A" doesn't extract the level of detail that DAC "B" can. That is to say there's more detail in the recording that I am missing with a different DAC. It's not noise from either DAC. But this is an entirely different discussion...)

The Benchmark is a fine amplifier for sure, one of the very best that can be purchased today.
That said, if your hearing differences in cables and DAC's, unless one of them is seriously compromised against known standards that have been in place for decades, what your hearing is what your eyes tell you to hear.. I suggest using some friends to hold tightly bias controled DBT listening so as not to let improper procedures lead you down a fictional path.
Good Luck.

 

[RobS]

The Benchmark is a fine amplifier for sure, one of the very best that can be purchased today.
That said, if your hearing differences in cables and DAC's, unless one of them is seriously compromised against known standards that have been in place for decades, what your hearing is what your eyes tell you to hear.. I suggest using some friends to hold tightly bias controled DBT listening so as not to let improper procedures lead you down a fictional path.
Good Luck.

I think the differences I am hearing with XLR cables might have something to do with its design, electrical characteristics or perhaps one having higher capacitance. For example, using a pair of 6ft. Canare L-4E6S straight from my DAC to the AHB2, I am hearing a boomier bass whereas with my 6ft pair of Belden 1800F cables the bass is thinner, not as overly present (which lines up with other owners' experience) but there is a tad bit of transient overshoot. I think that is to be expected between cables used for microphone/live stage use vs digital connections. It's been awhile since I've reviewed the spec sheets but I recall there were measurements that correlate to what I've heard.

I understand folks here call into question folks' subjective findings and the usual audiophile lingo to describe them, but I do think the differences I speak of are probably explainable when looking at the specifications and design.

In regards to DAC differences it depends, some can be obvious and others a lot harder to notice. But this is heading in the subjective territory this forum frowns on so I will stop here, but I found the AHB2 to be exceptional at revealing these differences (even the minute ones) among other amplifiers I've tried in its price class and below.

Well you'd have to define what you mean by resolution for an amplifier - in terms of normal amplifier metrics.

I think I elaborated in the rest of my post what I meant by resolution.

 

[Sal1950]

For example, using a pair of 6ft. Canare L-4E6S straight from my DAC to the AHB2, I am hearing a boomier bass whereas with my 6ft pair of Belden 1800F cables the bass is thinner, not as overly present (which lines up with other owners' experience) but there is a tad bit of transient overshoot. I think that is to be expected between cables used for microphone/live stage use vs digital connections.

If correct (and I don't believe it is) why would you ever use a cable in your system with known electrical characteristic that would modify the linearity of it's response?

I think that is to be expected between cables used for microphone/live stage use vs digital connections. It's been awhile since I've reviewed the spec sheets but I recall there were measurements that correlate to what I've heard.

Your letting your assumptions and eyes affect what you hear.

 

[antcollinet]

I understand folks here call into question folks' subjective findings and the usual audiophile lingo to describe them, but I do think the differences I speak of are probably explainable when looking at the specifications and design.

Thing is - for any line level audio cable of even vaguely sensible design (and I don't know of any that are not sensible) There are no electrical characteristics (Resistance, capacitance or inductance) sufficient to make an audible difference.

Not even to high audio frequencies, and certainly not an audible difference to low frequencies such as those bass effects you describe.

 

[RobS]

If correct (and I don't believe it is) why would you ever use a cable in your system with known electrical characteristic that would modify the linearity of it's response?

I wouldn't and supposedly neither cable should affect the linearity of the response. As to sighted bias, I am not sure that is involved in my assessment of the differences here because I'm wholly indifferent to either cable and not trying to justify a $10K cable purchase (which neither of these two cables come anywhere near that). I was just speculating that perhaps I'm using them outside of their intended use case (one which really should be for microphone use only) which might cause these audible anomalies.

 

[RobS]

Not even to high audio frequencies, and certainly not an audible difference to low frequencies such as those bass effects you describe.

Higher capacitance cables can cause high frequencies to rolloff but those are usually runs >100m or if the source impedance is high. Amir measured this before.

 

[quattro98]

I think the differences I am hearing with XLR cables might have something to do with its design, electrical characteristics or perhaps one having higher capacitance. For example, using a pair of 6ft. Canare L-4E6S straight from my DAC to the AHB2, I am hearing a boomier bass whereas with my 6ft pair of Belden 1800F cables the bass is thinner, not as overly present (which lines up with other owners' experience) but there is a tad bit of transient overshoot. I think that is to be expected between cables used for microphone/live stage use vs digital connections. It's been awhile since I've reviewed the spec sheets but I recall there were measurements that correlate to what I've heard.

I understand folks here call into question folks' subjective findings and the usual audiophile lingo to describe them, but I do think the differences I speak of are probably explainable when looking at the specifications and design.

In regards to DAC differences it depends, some can be obvious and others a lot harder to notice. But this is heading in the subjective territory this forum frowns on so I will stop here, but I found the AHB2 to be exceptional at revealing these differences (even the minute ones) among other amplifiers I've tried in its price class and below.


I think I elaborated in the rest of my post what I meant by resolution.

There are electrical differences between L-4E6S and 1800F, but these won't result in an audible difference in sound (unless there's something very strange with your DAC).

Both are fine choices for analog line level audio. Microphone cable is completely fine for line level audio, but it's over specified in that application. Simpler, cheaper, and thinner cables are ok for line level use (and no need for star-quad, but it doesn't hurt anything). FWIW, I use the Canare L-4E6S too. It's easy to buy from pro sources and flexible. I don't care that it's overkill.

As an example, Belden 8541 is for line level signals. The foil shield isn't preferred by some since it can cause some issues you don't get with a braided shield. In comparison to both of the above microphone cables, this is only 0.138 in (3.51 mm) in diameter. The microphone cables are a lot bigger.

 

[Kal Rubinson]

As to sighted bias, I am not sure that is involved in my assessment of the differences here because I'm wholly indifferent to either cable and not trying to justify a $10K cable purchase

Your sighted bias is subconscious and not subject to your awareness.

 

[Blumlein 88]

Could the better bass perception be related to the bias from the Canare being a larger diameter cable and the Belden is thinner???

Like Kal said, bias is not subject to awareness.

 

[RobS]

Your sighted bias is subconscious and not subject to your awareness.

I'm aware of that but the poster did say my "eyes" affected what I hear. (BTW If there's a clinician here who would like to perform a psychoanalytic evaluation to bring to light these subconscious biases, I'll be lounged in the listening chair ready)

But this stretch of conversation has detoured far from my original question, which was simply if there has been a new amplifier in the past couple of years that bests the AHB2 out in detail retrieval. Some amplifiers were mentioned that I will need to further review when I get the time.

 

[Blumlein 88]

I'm aware of that but the poster did say my "eyes" affected what I hear. (BTW If there's a clinician here who would like to perform a psychoanalytic evaluation to bring to light these subconscious biases, I'll be lounged in the listening chair ready)

But this stretch of conversation has detoured far from my original question, which was simply if there has been a new amplifier in the past couple of years that bests the AHB2 out in detail retrieval. Some amplifiers were mentioned that I will need to further review when I get the time.

Part of Kal's background:

Professor Emeritus of Neuroscience and Physiology at New York University School of Medicine​

 

[Sal1950]

But this stretch of conversation has detoured far from my original question, which was simply if there has been a new amplifier in the past couple of years that bests the AHB2 out in detail retrieval. Some amplifiers were mentioned that I will need to further review when I get the time.

It might even go a bit further back than you think.

"My Audio Legacy #6
Amplifiers have been quite excellent for more than a few decades, offering few opportunities for engineering breakthroughs. There are significant differences in topology, measured specifications, physical design, and cosmetics, not to mention price, but the sound of all properly designed units is basically the same. The biggest diversity is in power supplies, ranging from barely adequate to ridiculously overdesigned. That may or may not affect the sound quality, depending on the impedance characteristics and efficiency of the loudspeaker. The point is that, unless the amplifier has serious design errors or is totally mismatched to a particular speaker, the sound you will hear is the sound of the speaker, not the amplifier. As for the future, I think it belongs to highly refined class D amplifiers, such as Bang & Olufsen’s ICEpower modules and Bruno Putzeys’s modular Hypex designs, compact and efficient enough to be incorporated in powered loudspeakers. The free-standing power amplifier will slowly become history, except perhaps as an audiophile affectation. What about vacuum-tube designs? If you like second-harmonic distortion, output transformers, and low damping factors, be my guest. (Can you imagine a four-way powered loudspeaker driven by vacuum-tube modules?)
Peter Aczel"

 

[gfinlays]

But this stretch of conversation has detoured far from my original question, which was simply if there has been a new amplifier in the past couple of years that bests the AHB2 out in detail retrieval. Some amplifiers were mentioned that I will need to further review when I get the time.

In a word, no. The AHB2's noise and distortion levels are so far below audibility that there is no audible improvement that can be achieved.

Anyone looking for "better" than the AHB2 is chasing rainbows and unicorns.

 

[antcollinet]

Higher capacitance cables can cause high frequencies to rolloff but those are usually runs >100m or if the source impedance is high. Amir measured this before.

Well exactly - are you using 100m runs of cable? And that is only the high frequencies.

This is not an application I've ever seen in home audio. I"ll admit I didn't qualify my statement with "in normal home audio applications"

EDIT - though I did specify "sensible designs". 100m cables for home audio use are not sensible.