Review and Measurements of Benchmark AHB2 Amp

[misterdog]

I can understand how some can describe the accuracy of near zero, added distortion, as cold and clinical.

Sibilance however, suggests something else.
I have Quad 989 ESL's with supertweeters and there is no sibilance, through either analogue or digital source.

 

[HarmonicTHD]

I can understand how some can describe the accuracy of near zero, added distortion, as cold and clinical.

Sibilance however, suggests something else.
I have Quad 989 ESL's with supertweeters and there is no sibilance.

Correct. And that is why I give a hoot about subjective comments on listening impressions.

I run super clean amps (SINAD above 110dB) also into KEF Ref 3 - sounds wonderful to me (and this my subjective impression only valid to me) of which everyone else should also only give a hoot about.

 

[misterdog]

The ironic thing to me is that when music has distortion used as an effect, Bjorks, Homogenic for example, the music used be unlistenable to me on previous systems which added more distortion.
To the extent that I sought out alternative versions, in the belief that I had a faulty copy.

Maybe some people are more sensitive to hearing distortion - who knows.

 

[andrewngu]

I'm wondering if using its matching preamp would have given a much better sound vs. plugging my DAC straight into it. I also didn't bother playing with speaker position as they were optimized for the Naim, which was a laborious and meticulous exercise. It's also quite possible that I had gotten used to the Naim sound, making the difference too vast to adjust to. I guess that's how they getcha.

 

[HarmonicTHD]

I'm wondering if using its matching preamp would have given a much better sound vs. plugging my DAC straight into it. I also didn't bother playing with speaker position as they were optimized for the Naim, which was a laborious and meticulous exercise. It's also quite possible that I had gotten used to the Naim sound, making the difference too vast to adjust to. I guess that's how they getcha.

When doing your listening tests:
Did you match levels and if yes, how?
Did you test blind?

 

[andrewngu]

No, I didn't do a blind test or tried level matching. My evaluation was purely subjective and admittedly, probably of little value to anyone on this forum. I just played my favorites at a few different levels. I went into to this, fully hoping that I could replace my expensive, poor measuring gear with one of the best measuring amplifiers of all time and found that it wasn't the case. I really wanted to like this amplifier, otherwise I wouldn't have gone through the trouble of ordering it, buying all the cables, setting it up, only to return it.

 

[Geert]

I also didn't bother playing with speaker position as they were optimized for the Naim, which was a laborious and meticulous exercise.

I´m glad you mention this yourselves, because it was the first thing that came to mind when I read your earlier message. There's absolutely nothing wrong with the sound of the AHB2, so if the sound is as terrible as you explained look elsewhere.

Did you ever perform a measurement at your listening position? Are you using room eq?

 

[andrewngu]

I never said there was anything wrong with the amp, seems like there are plenty of folks who love it and are happy with it, which is awesome. In my case, it's purely a matter of my very subjective taste. I didn't perform a measurement with the AHB2, but have done it with my old amp in an attempt to integrate a sub into my system. Not using room eq, but have some room treatment to try and smooth out known room modes.

 

[HarmonicTHD]

No, I didn't do a blind test or tried level matching. My evaluation was purely subjective and admittedly, probably of little value to anyone on this forum. I just played my favorites at a few different levels. I went into to this, fully hoping that I could replace my expensive, poor measuring gear with one of the best measuring amplifiers of all time and found that it wasn't the case. I really wanted to like this amplifier, otherwise I wouldn't have gone through the trouble of ordering it, buying all the cables, setting it up, only to return it.

I like your honesty, I really do. Some come here with a different attitude but you seem at least be open to other factors being at play. And nothing wrong with your preferences.

But maybe and just maybe with a lot of ifs. If you would have done it maybe there would not have been such if any significant audible difference at all and you would have been happier with your purchase. Maybe next time.

Btw. What was your other amp again? Because as it has been stated many times here. What can be heard (in level matched blind test) can also be measured and it could be interesting if your impressions can be traced back to measurable differences (or if they were truly due to unleveled and sighted tests).

 

[andrewngu]

My other amp is the Naim Uniti Nova. Its measurements can be found on Stereophile for anyone who might be interested

Naim Audio Uniti Nova integrated amplifier-media player Measurements

Sidebar 3: Measurements

www.stereophile.com

 

[elvisizer]

sibilance is a strange one though- AHB wouldn't be adding that . . . maybe your old amp was masking sibilance in your source?

 

[andrewngu]

sibilance is a strange one though- AHB wouldn't be adding that . . . if you're listening to vinyl, maybe your old amp was masking the sibilance in your source?

Yes, it's quite possible that the high frequencies of the old amp are more muted or less revealing than the Benchmark and my ears might have perceived the newly discovered detail as sibilance. Whatever it was, I found the sound to be fatiguing. I'm fully aware that we are all victims to our subjective biases, but I had my previous amp's box out and ready to go and was fully prepared to list it on Audiogon, based on my research on the Benchmark.

 

[andrewngu]

I like your honesty, I really do. Some come here with a different attitude but you seem at least be open to other factors being at play. And nothing wrong with your preferences.

But maybe and just maybe with a lot of ifs. If you would have done it maybe there would not have been such if any significant audible difference at all and you would have been happier with your purchase. Maybe next time.

Btw. What was your other amp again? Because as it has been stated many times here. What can be heard (in level matched blind test) can also be measured and it could be interesting if your impressions can be traced back to measurable differences (or if they were truly due to unleveled and sighted tests).

Not sure if its worth mentioning, but what prompted me to order the Benchmark was the success I had in trading in my Focal Stellias ($3k and panned by Amir) for the Dan Clark Audio Aeon Noire ($800 w/ superb measurements). Who wouldn't be open to trading down for better performance while saving some coin? I was hoping I could achieve similar results with my 2 channel set up, but for my room and to my ears, this unfortunately wasn't the case.

 

[HarmonicTHD]

My other amp is the Naim Uniti Nova. Its measurements can be found on Stereophile for anyone who might be interested

Naim Audio Uniti Nova integrated amplifier-media player Measurements

Sidebar 3: Measurements

www.stereophile.com

I see. Certainly not SOTA with quite some noise ca 60 to 70dB and SINAD also btw 60 and 70dB and a ca 1dB drop in the frequency response btw 5 and 20k. Hard to say if the crooked FR vs the straight one from the AHB caused the difference in perception - yes maybe. My money would be first on the non matched levels.

You can also play with the toe in of the KEFs if you perceive it as too bright or EQ as the KEFs have nice directivity and get REW to quantify your preference in FR. At least this way you can come back to it for sure when you introduce changes.

Anyway. You made your decision and now enjoy.

 

[radix]

Yes, it's quite possible that the high frequencies of the old amp are more muted or less revealing than the Benchmark and my ears might have perceived the newly discovered detail as sibilance. Whatever it was, I found the sound to be fatiguing. I'm fully aware that we are all victims to our subjective biases, but I had my previous amp's box out and ready to go and was fully prepared to list it on Audiogon, based on my research on the Benchmark.

I'll just toss this out there just in case. Is the EQ turned off on the RMI, if it was setup for your naim? Also, what source do you use, and did you setup any EQ for the Naim there?

It may be that how your speakers were setup for the Naim might not be how they need to bet setup for the Benchmark, if the person doing it was correcting for something on the Naim. You might try just moving your head around or try different seating positions.

I like to use a UMIK with REW to measure.

 

[andrewngu]

I'll just toss this out there just in case. Is the EQ turned off on the RMI, if it was setup for your naim? Also, what source do you use, and did you setup any EQ for the Naim there?

It may be that how your speakers were setup for the Naim might not be how they need to bet setup for the Benchmark, if the person doing it was correcting for something on the Naim. You might try just moving your head around or try different seating positions.

I like to use a UMIK with REW to measure.

I actually don't use EQ with the Naim. It's a streamer, DAC, amplifier all-in-one. I purchased the RME ADI to use it with the Benchmark. When I was testing the Benchmark, I had my iMac m2 Air -> RME via USB -> Benchmark AHB2. I'm wondering if having a preamp between the DAC and the amplifier is the right way to fairly evaluate the AHB2.

 

[HarmonicTHD]

I actually don't use EQ with the Naim. It's a streamer, DAC, amplifier all-in-one. I purchased the RME ADI to use it with the Benchmark. When I was testing the Benchmark, I had my iMac m2 Air -> RME via USB -> Benchmark AHB2. I'm wondering if having a preamp between the DAC and the amplifier is the right way to fairly evaluate the AHB2.

Any pre-amp would only deteriorate the signal, already by adding another processing step in between. The RME please puts out a signal as clean and as strong as it gets.

Only EQ, level matching and blind test will help (you can use the EQ from the RME) and all verified by REW. Everything else is just a blind wild guess.

Audio Blind Testing - You Are Doing It Wrong! (Video)

Just uploaded a video on the basics of performing controlled tests in audio. It was motivated by saving myself text in having to write all of this down when telling someone who to do these tests right. And as a counter to a few online personalities to keep saying they do "blind" tests yet when...

www.audiosciencereview.com

 

[pma]

Any pre-amp would only deteriorate the signal

This is oversimplified. In case of a well designed low noise preamp, it may and often will improve S/N and dynamic range. It allows for DAC to be set at maximum output (no digital attenuation) and then uses analog level control. So, it depends. On both DAC and preamp design. In many cases, I have measured better results with a preamp than without it.

 

[andrewngu]

This is oversimplified. In case of a well designed low noise preamp, it may and often will improve S/N and dynamic range. It allows for DAC to be set at maximum output (no digital attenuation) and then uses analog level control. So, it depends. On both DAC and preamp design. In many cases, I have measured better results with a preamp than without it.

this makes sense to me. i was under the impression that using digital volume control results in a lowering of dynamic range.

 

[HarmonicTHD]

This is oversimplified. In case of a well designed low noise preamp, it may and often will improve S/N and dynamic range. It allows for DAC to be set at maximum output (no digital attenuation) and then uses analog level control. So, it depends. On both DAC and preamp design. In many cases, I have measured better results with a preamp than without it.

No, not in the specific case here of which the OP is talking about, where an RME ADI2 DAC feeds an AHB2. Even if you would find a preamp with a better gain performance eg SINAD over output voltage than the RME, the result will not be audible (yes of course it can be measured). Run the numbers and I am sure you come to the same conclusion for this particular case.

The differences the OP perceives are most likely due to unmatched levels and sighted tests of AHB2 vs a very poorly performing Naim amp (ca 60dB SINAD and a ca. 1dB roll off on higher frequencies).