Benchmark AHB2 power amp impressions?


Does anyone have any opinions/info to share about the new Benchmark AHB2 power amp? Do the company's assertions about drastically reducing noise and distortion ring true? Thanks to all.  
ranchhand1
I have the same questions that ranchhand1 has above about the Benchmark Media's assertions about drastically reducing noise and distortion, etc.

The review, by Paul Seydor of the Benchmark Media AHB2 power amplifier ($2,995) in The Absolute Sound (#262), was very interesting.  He gave it a “high, enthusiastic, and confident thumbs up. The product review was interesting and alerted me to a new product that I had not heard of before.  Please note that reviewers, friends, Audiogon, etc. recommenations are interesting BUT I always listen and decide for myself.

Since the Benchmark DAC2 DAC has its own volume control, it means it can be connected direct to the power amplifier (no pre-amp).  The Benchmark AHB2 power amplifier can also be used in stereo or a mono only version for increased power.

I am not in the market for new products since I am very happy with my Bricasti M1 DAC and my Hypex NCore NC400 mono block power amplifiers. However, if I was in the market, I would review the Benchmark AHB2 and the Benchmark DAC2 DAC.   I like the fact that Benchmark products are engineered and manufactured in the USA. Please see:

http://benchmarkmedia.com

I like their transparent audio path and their design looks very good.   Does anyone have any comments, or experience, with the Benchmark AHB2 power amplifier and/or the Benchmark DAC2 DAC?   Thanks.   

I have been using the Benchmark DAC2 now for several years now. I could not be happier with this unit. I use it on my office system as a digital pre-amp. I also use a FM- Tuner with this DAC since it has 2 analog inputs. I have 2 other computer based sources going into the digital inputs of the DAC. All the inputs sound great. I have very good equipment for an office system. The weakest link is not the DAC.

1) KEF LS50 speakers
2) Torus RM15 power
3) Magnum Dynalab tuner
4) Benchmark DAC2
5) Audience speaker cable and  balanced interconnects
6) Parasound  A23 amp
7) Roon and Tidal for FLAC digital music sources

I used to have a BAT VK-42SE pre-amp in this mix with the Benchmark DAC2 serving as a DAC and not a digital pre-amp. The sound was a little fuller with the BAT but I preferred the sound I have now with the DAC2 alone. It sounds realistic and clean.  I sold the BAT. The BAT was a 6K item when It came out and the new replacement for it is a 9K piece. A lot of people may prefer the fuller sounding BAT in the mix.

My goal now for almost 2 years is to get the Benchmark AHB2 amp. Once certain business investments are completed I will jump at getting this amp to replace my Parasound A23.  Cannot spend money on audio at the moment.

I have heard quite a few DACs over the last few years, The best being the Resonessence Labs MIRUS DAC and the PS Audio DirectStream. The DAC2 was not played on the same level equipment (especially amp) as the other 2 so it is not a fair comparison. However, using the DAC2 for years now has not made me wish I had something different. I think it is pretty close in performance to the top 2 DACs I have heard.

Benchmark is based in Syracuse, NY. I have family in that town so I am also happy to support business based there. Especially when I am so happy with their products and email support.


I had a chance to audition the AHB2 in my own system and later on also received the DAC2 to complete the audition (thanks to the local dealer for making this happen).  However this was maybe 9 months ago so please take into account that my observations are largely based on what I can recall.
The AHB2 is a very well built amp and its got a nice heft to it despite its small size, which is plus when moving it around in the rack.  Fit and finish is first class - no complaints there.  Since it was a new unit I gave it some 50 hours of burn in before critical listening
I drove it first with my CAT SL-1 preamp (AHB2 set on mid gain sounded bland so ran it on high gain).  It is indeed a QUIET amp - with the pre on mute, not a sound with my ears to the speakers (bookshelf Green Mountain Audio). To me the sound was very clean - almost too clean.  Abundant micro details and a black background though a little lean overall.  Overall it sound a little sterile for my taste - something like what you might expect to hear in a recording studio monitor I assume (I was reminded a little of my listening session with Genelec studio monitors which had a similar sound signature).  Pace and rhythm was very good, mids were very clean  but the overall presentation lacked something (the emotion?) which to my mind is that critical glue that binds all the elements of the recording and presents it as music.
Next up I drove it directly from the analog outputs of the DAC2 (DAC2 set to 0dB and AHB2 to low gain as is recommended).  This combination felt like a better match (even quieter and with more perceived drive) but the sonic signature didn't change much - and it was still a little lean and that sterility factor persisted - perhaps even more so.
I appreciate all the technology that has gone into making the AHB2 and the small form factor, great finish and substantial 190W @4ohms from a small chassis, But I wan't swayed enough by the sound to pull the trigger to purchase it.  Also, my own sense is that while the amp has three gain options to make it a suitable match for different pre/DACs etc, it was probably mostly conceived as a partner for the DAC2.
YMMV

I just got an AHB2 this past week. After using and moving heavy amps for a long time (Pass, McIntosh, etc) I decided I want a lighter, smaller amp. After reading reviews on the Benchmark, I decided to try it.

I’d echo many of jitterbug’s comments, though I don’t find it ‘sterile’. Perhaps because it’s so quiet and we tend to get used to other ‘noise’ in the music it seems that way, I don’t know.   I’ve been able to hear separation of instruments more clearly than ever before (at least to my auditory memory) and the level of detail is really something.   In familiar recordings I’m also hearing things I don’t recall hearing before. So far it’s been a real pleasure!

I’m using it with a Cambridge 851d as a preamp/dac and my current speakers are Harbeth C7-ES3’s. I currently stream via Apple TV to the Cambridge, and also use an Oppo 93 as a transport.

I plan on moving to a Benchmark DAC-2 HGC shortly as the Cambridge has developed a quite noticeable transformer hum.  


I Have owned a pair of AHB2 as monoblocks for a year, and they replaced a pair of Marantz MA9S2 with no regrets. Yes they are quiet and clear, more so than the Marantz.

It does not sound Sterile to me , but the partnering electronics have to match. In my system the Hegel P30 preamp sounds a little too aggressive on the AHB2, but the Cambridge 851E gives it a happy marriage. 

I have better amps but for the price, size, performance and convenience , the AHB2 is a great buy. I plan to keep them for a long time . 
Benchmark make great products - many of them "giant killers" for a good price. To be honest I don't care for the Marantz sound at all but I know many like the smoother more laid back or "natural" presentation they are known for.
If THD and S/N were all the buzz, we would never have things like tube amps, SETs, etc. where even 3% THD is not far from the norm, as well as s/n < 100dB.
It is no wonder that many audiophiles from the real world (you can find those only on various audio forums such as this one) assess this amp as "too clinical", "no emotion", etc. This is in sharp contrast to assessments of so called professional reviewers. Ask yourself why.
I'll start by asserting the following: neither Revel Ultima Salon 2 nor AHB2 that were used in most professional reviews are exceptional. Yes, you will find many praises for the two. But the MAJORITY of the real world audiophiles have already spoken. Nowadays, many people who bought Salon 2s regret their decision. MANY of them try to sell their speakers in very good condition on agon for less than half of the $22k msrp price, e.g. $10k, but are unable to. The word spread. The speakers were not worth $22k to begin with.
What about AHB2?
I'll answer by asking what about it's frequency range? What about slew rate? Rise time? It is widely known that as far as human ear is concerned both frequency range and slew rate are much more important than THD and other parameters (they are important, but not to the extent these other ones are). Ideally, the frequency range of an amplifier should be in the range 3MHz or more, but definitely more than 1MHz. Thus it is much better to design an amplifier with lower s/n and/or THD, and correspondingly higher frequency range and slew rate / rise time than vice versa. Only then you will get the so called "organic" sound, yet detailed and "you are there", "non fatigue" etc.
@navrsale 

You seem to be an expert. Could you please provide some data on the slew rate etc. of the Benchmark amp?
@navrsale 

AHB2 Slew rate is 16V/uS and rise time at 3.5mS and a bandwidth of 200kHz.

I can't understand why you think a 3 Mega Hz bandwidth is required in an audio amplifier. 

You seem to prefer higher distorting euphonic designs and there is nothing wrong with your taste.

However, some audiophiles are impressed and interested in the market leasing high fidelity that the AHB2 amp offers. Especially the performance at low levels like 1 watt where this amplifier excels just as amazingly as it does bridged at 300+ watts.
@shadorne 

I can't understand why you think a 3 Mega Hz bandwidth is required in an audio amplifier.

Maybe he can hear very high frequencies :)))
I wonder pairing the AHB2 with a tube preamp would be a good combination. I like how you can change the gain with both unbalanced and balanced cables. The amp, from what I've read, can sound quite clinical to some. With a good tube pre, some slight smoothness is what would make a great sounding system.
I will eventually be comparing this to an Ayre V5xe with Harbeth P3er speakers. Will follow this thread. 
Just curious if anyone purchased the Benchmark brand Canare speaker cables with the "special" connector at one end (for the amplifier). The interconnects they sell look like they are the same Beldon cables you can buy thru Blue Jeans just customized for Benchmark. 
I bought the cables.  They are so reasonably priced I thought it was worth a try.

The Speakon connector is very easy to use; trying to fit my other cables' spades into those insulated posts with downward-pointing entrance slots is a pain.  The back of the amp is really tight on space.

I don't feel the Benchmark cables were an improvement... it was more of a wash. Guess I thought something was not quite there, and in the end I put back my Omega Mikros, even though it's less convenient.  But the fact that the difference was not hugely noticeable (in my system) points to the Benchmark cables as being a good value.
@mrppv  

A wash is how it should be. If everything is working fine and your amp and speakers are well matched then the cables should make no discernable audible difference. 
I would guess a dead quiet amp like the Benchmark may highlight cable differences more. Just a guess
@aberyclark 

Try disconnecting your amp at the amplifier end and listen to the noise of the speaker wires. Generally speaker wires run at high signal levels and speakers are rather inefficient and are rarely able to pick up any RF/EM speaker cable noise to be even close to audible.
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I have a pair of Ming Da 3008a monoblocks.  40 watts of SET.  They play as loud as a 100 watt SS amp.  I never forgot when I first heard them.....how the music stopped and started on a dime with the best separation and black background.  It was a quick education on cross over distortion.  If the Benchmark amp could achieve this, with say a tubed CD player, I would be interested.  On the other hand it seams as if the amp is at its greatest when paired with the DAC.   
I purchased enough of the AHB2 amps to tri-amp my speakers, and these are truly world class amps.  

Having an invisible noise floor means you can hear so much more detail that was previously hidden in the background (at loud or even soft volumes).  You can also hear things at low volumes that no other amp I have heard is capable of, and measurements of what this amp can do at the 1 watt and below clearly show it's distortion is the best out there.  Hint: ultra low distortion at 1 watt and below really matter if you want detail at low volumes.

This amp is absolutely fantastic from an engineering and specifications perspective, and the real world listening is the same; it can make hairs on your neck stand up because it can sound that real if the rest of your system can reproduce the required dynamic range with ultra low distortion.

The dynamic range and driver control in my setup is truly unreal.  To be fair, my setup also involves using active XOs that employ FIR filters, and of course I removed the passive XOs from my speakers to achieve the best possible damping factor.  I have all drivers time aligned as well.

That said, I did try several amps in the $1k-3k category in my tri-amp setup, and the Benchmarks are absolutely some of the best amps on the market.  I've shown my system to one dealer that does $100k+ setups and he couldn't believe the sound of my setup.  Google the measurements and read the reviews such as the one Stereophile did.

I totally understand if someone likes the warm sound of tubes though, but if you want to hear exactly what was recorded in ultra high fidelity with the best possible dynamic range, these amps are likely the best option for you.

Since I'm a decent guy, if you are local to Columbia, SC maybe I can let you hear what I'm talking about.  Send me a PM if this is the case because I don't come on here very often...
Thanks for invite. People must love the amp...not may used (or they return them quickly after purchasing). I'm hoping, after new year, to try one in my system. I have to say, my NuForce STA200 is sooo good as I have everything dialed in great. However, the thought of the ultra quiet Benchmark, with my RP-5 tube preamp and ZU omen defs really sounds appealing.
I've had the AHB2 for the past few weeks, and absolutely love it!  Paired it with Hyperion HPS-738s and Dynaudio EX34s.  Dead quiet, wonderful bass control.

I've installed some Neutrik NL2FX connectors on my speaker cables and not sure how much of a difference it makes in comparison to the regular binding posts, but I sure love having the option.  It's a solid connection for sure.

So much impact & clarity for such a small amp.  Thinking about picking up another one in the near future to run as monos.


I would probably buy the actual Benchmark speaker cables. I believe on another forum, a couple said they were quite good.
I have an all Benchmark system - DAC3L > HPA4 pre > 2x AHB2 in bridged mono.

I completely disagree with the comments that the AHB2 is clinical sounding. To me it sounds beautifully balanced and fully capable of reproducing the full range of musical colours and emotions. Notice I say reproducing. The AHB2 is definitely not a coloration machine for injecting flavour, it's an 'as is' device for reproducing whatever is provided by the source. 

I've had 6-7 amplifiers of all types through my system in recent years and have found that amplifiers with 'flavour' eventually become tiresome as the 'thumbprint' is heard on everything that passes through them. I prefer the revealing, chameleon like, character of the AHB2 where the sound changes with the qualities/intricacies of the source. 
I also appreciate these qualities in the ATC monitors I'm using in my system and find the combination musically compelling. YMMV.
@tobes thanks I am considering Benchmark AHB2. How does it compare to latest Class D offerings like Legacy Powerbloc , ATI AT523NC , Nord , Apollon and Hattor etc?. Did you ever get a chance to compare with Class D amps?.
I had a Halcro MC30 class D amp for a while which I really liked. It was also very revealing and not overtly coloured. 
I sold that amp mainly because the highish gain wasn't a good match with the preamp I was using at the time.
Hard to make a fair comparison because I didn't own both amps at the same time and the other components were different. My feeling is that the AHB2 may be superior at low levels, in the high frequencies and in terms of low noise floor. However the Halcro was still impressive in those respects, so it's relative I guess. 
My thoughts aren't really much help to you because I never did the direct comparison and the Halcro isn't necessarily similar to the other Class D amps you mention. 
@aberyclark  Before u buy the Benchmark cables read the following review. 

https://www.dagogo.com/benchmark-audio-dac3-dx-ahb2-amplifiers-review/

I just sold the AHB2 because of a change in system. However, I loved this amp and found it clear and fatigue free. Not clinical at all.  I may buy this amp again if I decided to keep a second set of office speakers.
Thanks, yyzsantabarbara, for the recommendation of the review. Persons who ignore my advice regarding cables will have diminished sound quality, especially if they ignore aftermarket power cords and USB cable.

It is critical to explore the three gain settings on the back of the amp; these make a significant difference and are a feature not found on most amps at the price point.

In recent months I have been exploring my discovery of the huge advantage of the Schroeder Method, doubling ICs. You can read about it as well at Dagogo.com in the Audio Blast: the Schroeder Method of Interconnect Placement. This is no joke, and the Benchmark components rise up to a completely different level of performance than with single IC.

The Schroeder Method has its own warnings and restrictions on use, and it is a do at your own risk activity. I have been running Schroeder Method with the DAC3 DX and AHB2 pair in Mono for a while now and I will not return to single IC use as it is insipid. Anyone using single IC with this combo is getting paltry performance from the components.

Anyone who thinks the performance could not improve that much is wrong. Most audiophiles have no clue how much improvement audio systems can undergo, and they typically are skeptical of large performance gains due to ignorance. They stop seeking huge gains way too early, and they begin to putz around with tweaks, anchoring their rig to the lower level sound. I don’t care to do that.

Currently I have the combo set up with the PureAudioProject Trio15 Horn 1 Speaker (reviewed) and it is performing at a level not achieved in the review through any system using single ICs. The PAP Horn 1 and Benchmark gear are an excellent combo. I have put other components together with it using Schroeder Method and it has performed similarly above the threshold of the review performance. Loom of cables being reviewed are well known and lean toward the affordable end of the spectrum.

If you wish to try Schroeder Method you may contact TEO Audio or Audio Sensibility, as both companies are making a double interconnect as per Schroeder Method. TEO does not do XLR typically, but Audio Sensibility does. I am currently undergoing a review of the Audio Sensibility offerings in relation to Schroeder Method. 

If you wish to explore Schroeder Method further, see the thread in the Cables forum with my name. People are testing it out and sharing their findings.

The sound quality/performance potential of the DAC3 DX and AHB2 is far better than even Benchmark knows. Schroeder Method reveals a much greater sound quality instantly. I am not interested in debating/arguing my points.

BTW, upgrade the fuse in the Benchmark components also for sound quality improvement. No, I do not want to debate that.

Sorry to skew the thread, but this is important for anyone who wants to find the limits of the Benchmark amp. The class AAA technology is far better than anyone realizes. As the Schroeder Method is NOT recommended for class D amps, this puts the AHB2 far, far ahead sonically.
I always love Dagogo reviews. The reviews are very "real world" without the influence of major manufacturer advertising dollars. 


Thanks for the advice. I never did agree that great amps are immune from cable swaps. In fact, I would think an uncolored amp like the Benchmark would highlight the differences even more since one would have a "cleaner (FLOABT)" path to the source material being played and difference would stand out more. I currently use Canare start quads with my system, so it probably would not make since to buy the Benchmark cables anyway. I have been considering ZU event cables.

I believe when some reviewers say the amp is sterile, they are hearing is the actual weakness of the source material. So much music , especially in rock and pop, has been poorly recorded, mastered, etc...that those faults come to the forefront with a revealing system.


@douglas_schroeder I've read a bit of the double interconnect thread. It seems people are experimenting by using 'Y' adapters for RCA interconnects. I presume you are using balanced connections with the Benchmark gear - have you done that by bringing both cables into the balanced shell and double terminating on the single connector?
May I also ask which fuse brand you substituted into the Benchmark gear? 
BTW, I agree about the power cords. I use only the relatively inexpensive VH Audio DIY cords with Furutech connectors - but would never go back to stock.
As you know the DAC3 IEC inlet positioning makes it impossible to use round barrel IEC connectors without obscuring the usb socket. So I initially used a just a decent shielded cord I had lying around with moulded connectors.
Later I decided to re-terminate one of the VHA cords (which I'd used with other DAC's) using the compact Furutech rhodium plated IEC. I was shocked by the improvement. 
I'm sure if John Siau reads this he'll be doing a double face palm.
Kal Rubinson who writes the Multi-Channel/Surround Sound column in Stereophile every month uses 3 of these AHB2's in his 5.1 setup at home.  Pairs them with the Audio Research Multi Channel Pre-Amp and says its an amazing combo. I already picked up the ARC Pre so hope to get the AHB2's down the road.
Thanks for the comments, aberyclarck and tobes, good info.

Any amp can be made to sound relatively more or less sterile; so much depends upon the rest of the system. As well, one man’s sterile is another’s "accurate", etc. However, the amp is quite a bit less colored than many other SS and tube amps. If a person is used to and adores the thick, syrupy, darker sound of tubes, they won’t like the AHB2.

Regarding the Schroeder Method, I am using Y cables from Audio Sensibility currently (previously I had obtained my own Y cables from online and pro sound sources). For RCA both Y cables are identical, but for XLR one needs a "splitter" Y cable and then to reverse it a "joining" Y cable. My terms for lack of better description. I am very pleased with the quality of the Audio Sensibility Y cables.

I have used Clarity Cables XLR in Schroeder Method, and am now reviewing a full set of another fairly affordable cable manufacturer. The power cord of this manufacturer also uses a slightly smaller round barrel on the IEC, so I can use these wonderful power cords. They are making a nice improvement over the older Harmonic Technology AC-10 Power Cord I had been using.

As with anything else, there is a spectrum of acceptance/rejection among engineers and designers/manufacturers. Some are very open and authentically interested in my ideas. Some are only interested in a good review, i.e. accurate and fair. I understand both perspectives and respect them.




@douglas_schroeder I'm going to make myself up a set of double interconnects to try between my Benchmark HPA4 and mono AHB2's.

I was initially going to make up XLR 'Y' adapters but was put off by the extra cable breaks and all the extra connectors required.
Of course for people who want to experiment extensively the adapters would be a good idea.

Since I'm using pro cables - Mogami Gold studio (W2534 star quad) - it's pretty cheap to make up double runs of w2534 with the same gold Neutrik connectors terminating both cables to a single XLR at both ends.    

I'll reply back with my results to the double interconnect thread as it'll be more relevant there.
Maybe I missed above, has anyone compared sound quality of using the preferred full balanced cable hook vs RCA to XLR cable or adapter?  My Rogue RP 5 pre only offers RCA main outs. Yes, I could purchase the RP- 7 , but that’s quite a bit more cash
@aberyclark Balanced will give you much lower noise floor and protection against issues of running longer cable runs. RP-7 is fully balanced which means you are getting way lot more than just XLR output.

What is your input to the preamp ?, does the source output a balanced XLR out?. Then you will have a technical benefit. If you can hear the difference or not will depend on many things. But you will get lower SNR, lower noise floor i.e from good implementations.  If you can afford balanced gear and balanced interconnects go for it.
My quick first impression with Benchmark AHB2 after couple of hours listening is that I think I have got myself the first serious HiFi product. Very good sound with my Paradigm Studio 40v3, well controlled across the spectrum, clean. Makes me turn up the volume without fatigue, at this point it seems like my speakers are the limit. I hate to compare with anything at this point without spending more time and doing a proper A/B testing. For such a small and not heavy amp it just makes great sound.

My signal chain is Tidal from Mac -> Audio-gd Master 5(with Dac, in pre-amp/dac mode) XLR out -> Benchmark AHB2.

The speaker cables from Benchmark seem to be of quite high quality. I am using the 10ft NL2 cable to speaker.
Geek101:
Thanks for the info. I wonder if make custom rca to XLR cables (ZU will make them) is a better option than using the adaptors that Benchmark sells?

I have the Star Quads, which I believe that are similar to the BM speaker cables, and have been quite happy. Good to hear you like the BM cables. 




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Nevrsale, you can't be serious talking that much crap about Revel Salon 2 speakers, some of the best ever made and that sound better than most that are far more expensive. What is your agenda for saying such nonsense? If you personally don't like them fine, but saying there is some sort of consensus that they are not expetional and not worth the money is pure BS