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  1. #1
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    Benchmark ABH2 Mono Block Consideration

    I’ve posted this inquiry in another forum as well with some interesting responses. So I’d welcome any experience from this forum as well

    I've owned the Benchmark ABH2 Amp for a few years but am now considering one two alternative upgrade paths:
    A New Amp or adding a second AHB2. If I purchase a new amp so far I like the Bryston 3BCubed which is a dual mono design with 200 watts into 8 ohms or possibly the 4BCubed at 300 watts. In either case this is more power than the single ABH2 at 100 watts into 8 ohms. However adding a second ABH2 increases the power per channel to 380 watts .
    So much for raw power. What about overall sound quality? The Bryston 3BCubed got an excellent review on Absolute Sound as an amp that would require significantly more $$ to better. Another review I read easily preferred the Bryston 43Cubed (300 watts per channel) over the ABH2.
    I'm in the process of completely upgrading my system after several years of the same components. I will shortly have:
    An Aurender N20 Streamer into an MSB Discrete DAC with dual power supplies feeding the single ABH2 which drives my Harbeth C7es-XD speakers.
    Everything will be new except the older ABH2. Hence the consideration of an amp upgrade.
    Now Benchmark will tell you that adding a second ABH2 is only needed when the single amp clips. Other than that there is no sonic benefit to adding a second. I Ffnd that hard to believe. I would think having a second would offer improved soundstage, separation and possibly better performance from the speakers. So my question is:
    Have any of you added a second ABH2 and if so what were the overall sonic benefits if any? Also any opinion or experience on the Brystons vs the Benchmark? Or any suggestions of a better upgrade path would be welcomed.
    jfrmusic

  2. #2
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    Re: Benchmark ABH2 Mono Block Consideration

    You will have a nice front end. You should first listen to your current amp with the new gear to get a point of reference.

    Then I would see if you can audition a Bryston amp. If no local dealer buy from online retailer with a return policy.

    Bryston is good gear. I have not heard Benchmark but know they are said to be very neutral.

    If you want a more lush leaning amp you might consider Pass. Several seem to like them with Harbeth. Sun Coast may have some trade-in models if on a budget. Pass will definitely be warmer then either Benchmark or Bryston.
    Aurender ACS10 w/Audioquest Diamond USB, Esoteric N05xd
    Mark Levinson #526, 534 & JBL 4367's
    Clearaudio Performance DC w/Maestro cart
    Clarus Concerto & their Crimson cables

    HT: Marantz AV8003, Linn 5125, JBL SAM3ha, Revel s30,
    SVS PC13 Ultra
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    Sony XBR-75X940D & BDP
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  3. #3
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    Re: Benchmark ABH2 Mono Block Consideration

    I personally don't like buying same model amp just to mono them. There could be better performance from higher power or better damping but it's still the same components on the inside. I figure for double the money I could just buy a better amp and achieve better sound. Just my opinion at this point.

    I actually bought same model Conrad Johnson and both amps converted to mono. I wanted to better drive a set of Dynaudio. I don't remember the sound quality improving.
    Aurender ACS10 w/Audioquest Diamond USB, Esoteric N05xd
    Mark Levinson #526, 534 & JBL 4367's
    Clearaudio Performance DC w/Maestro cart
    Clarus Concerto & their Crimson cables

    HT: Marantz AV8003, Linn 5125, JBL SAM3ha, Revel s30,
    SVS PC13 Ultra
    Transparent, Analysis Plus & Tributaries. PS Audio filtering
    Sony XBR-75X940D & BDP
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  4. #4
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    Re: Benchmark ABH2 Mono Block Consideration

    Yeah, Bryston and Benchmark sound different so you'd need to either know what change in sound quality you're looking for or compare them for yourself to decide if it is worth switching from the Benchmark AHB2 to a Bryston 4B3.

    I don't think adding a second AHB2 will do much for you unless you need the power. It doesn't lack drive capability even for very difficult speaker loads, and its channel separation and linearity is already extremely good.
    Neko Audio
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  5. #5
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    Re: Benchmark ABH2 Mono Block Consideration

    JFRMusic,

    My only experience with AHB2s is in the monobloc configuration. I found them to be very transparent and reflective of the signal they are fed. I still own the AHB2 monoblocs. I was so impressed with them I decided to upgrade my preamplifier. I have not paired them yet because when I added the preamp I also switched to winter, tube amp mode. I will pair the AHB2s with my new preamp in a month or two.

    I understand your inclination to upgrade what you might consider your weakest link or at least the last major component not upgraded. I am going through the same thought process with my DAC. Unfortunately I do not see a clear DAC upgrade choice.

    You are about to change major upstream components and your speakers. Listen to your system for a while before making any amplifier decisions. Let everything burn in then consider any next step. Patience grasshopper.
    Contributor to stereotimes.com

  6. #6
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    Re: Benchmark ABH2 Mono Block Consideration

    I must say, I can't see any good reason for thinking that bridging is of real benefit unless a single amp is lacking in output power. Using 2 stereo amps may offer a benefit if the system can be bi-wired (I don't subscribe to this theory myself) or bi-amped after the passive XO is changed to a pre-power amp active XO.

    In my search for a new ss amp to replace the SETs I'd previously been very happy using, I first bought an AHB2 on the rave recommendation of a fellow Avantgarde speaker user. Despite its "accuracy", dead silence and other nice features such as gain setting, I was disappointed to find that it was (I may have to duck behind the barricades now) drearily dull compared with what I was used to. It was an amp that never prompted the temptation to turn up the volume. It was more like "elevator music" (albeit dead accurate elevator music) than truly exciting music.

    I went on to buy or borrow many more amps of Class A (Sugden, Accuphase, etc), AB (Mark Levinson, GamuT, etc) and D (Devialet, NAD, etc) and ended up choosing the NAD M33 as my first choice - an unexpected result, I must admit.

    As you are looking for just a power amp, can I suggest you audition the NAD M23 amplifier, rated at 200 / 380 into 8 / 4 ohms. Forget that it's Class D (if that's a pre-existing concern for you) and just listen to it. It's a sensible price and will knock the socks off the Benchmark and most other amps anywhere near its price.

    Sorry if I replied in similar vein to the post you placed elsewhere, but I don't remember who I replied to.
    Sources - NAD M50.2 (streamer, CD player, CD ripper, hard drive music store)
    Amplification - NAD M33 all-in-one, NAD M12 preamp (in reserve), Atma-Sphere Class D monos
    Speakers - Avantgarde Duo XD, Avantgarde Duo (2006) - both aesthetically modified

  7. #7
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    Re: Benchmark ABH2 Mono Block Consideration

    Benchmark, is Class D. So I wonder if you only post to push NAD which would be lucky to be a sideways move at best. You say the NAD would best the Benchmark but seem to have no knowledge of the amp you speak to best. Your NAD fanboy dribble is tiring. No matter what a person asks you want to find a way to insert your NAD story.

    Quote Originally Posted by Hear Here View Post
    I must say, I can't see any good reason for thinking that bridging is of real benefit unless a single amp is lacking in output power. Using 2 stereo amps may offer a benefit if the system can be bi-wired (I don't subscribe to this theory myself) or bi-amped after the passive XO is changed to a pre-power amp active XO.

    In my search for a new ss amp to replace the SETs I'd previously been very happy using, I first bought an AHB2 on the rave recommendation of a fellow Avantgarde speaker user. Despite its "accuracy", dead silence and other nice features such as gain setting, I was disappointed to find that it was (I may have to duck behind the barricades now) drearily dull compared with what I was used to. It was an amp that never prompted the temptation to turn up the volume. It was more like "elevator music" (albeit dead accurate elevator music) than truly exciting music.

    I went on to buy or borrow many more amps of Class A (Sugden, Accuphase, etc), AB (Mark Levinson, GamuT, etc) and D (Devialet, NAD, etc) and ended up choosing the NAD M33 as my first choice - an unexpected result, I must admit.

    As you are looking for just a power amp, can I suggest you audition the NAD M23 amplifier, rated at 200 / 380 into 8 / 4 ohms. Forget that it's Class D (if that's a pre-existing concern for you) and just listen to it. It's a sensible price and will knock the socks off the Benchmark and most other amps anywhere near its price.

    Sorry if I replied in similar vein to the post you placed elsewhere, but I don't remember who I replied to.
    Aurender ACS10 w/Audioquest Diamond USB, Esoteric N05xd
    Mark Levinson #526, 534 & JBL 4367's
    Clearaudio Performance DC w/Maestro cart
    Clarus Concerto & their Crimson cables

    HT: Marantz AV8003, Linn 5125, JBL SAM3ha, Revel s30,
    SVS PC13 Ultra
    Transparent, Analysis Plus & Tributaries. PS Audio filtering
    Sony XBR-75X940D & BDP
    Parasound P6, MBL 8006b, Artisan speakers/subwoofer

  8. #8
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    Re: Benchmark ABH2 Mono Block Consideration

    Quote Originally Posted by Mr Peabody View Post
    Benchmark, is Class D.
    Quote is edited for brevity and emphasis.

    I am neither knocking nor promoting Class-D amplifiers. Not all Class-D amplifiers are equal. The same applies to all designs of amplifiers. Not all A, A/B, various tube designs, etc. amplifiers are equal. I only post the following from the Benchmark website to clarify comments some have made.

    My experience with Class-D amps has not been good but I keep trying because, and I repeat myself, not all Class-D amplifiers are equal. I have a new pair waiting for me to try when warm weather chases the tubes from my listening room.

    From the Benchmark website:

    The AHB2 is Not a Class-D Amplifier (And Here is Why)

    It seems like everyone is building class-D amplifiers, and some of them look very good on paper until you take a deeper dive into the specifications. Many class-D deficiencies are obscured by the fact that 20 kHz brick-wall filters are always used when measuring class-D amplifiers. These class-D test filters improve the measured performance, but they are not present when you connect a class-D amplifier to your speakers. Tweeters are not ideal low-pass filters and the class-D ultrasonic switching noise can produce audible effects when it interacts with the tweeters.

    Class-D amplifiers also suffer from poor THD performance at input frequencies above 1 kHz. Some of the newest Class-D amplifiers have impressive specifications at 1 kHz, when measured through a brick-wall 20 kHz lowpass filter, but this performance quickly degrades at higher audio input frequencies. It also degrades when driving low impedances and difficult reactive loads.

    For these reasons, Benchmark does not believe that class-D amplifiers are the best choice for reference-level performance. Nevertheless, class-D amplifiers are a great choice for cost-sensitive applications.
    Contributor to stereotimes.com

  9. #9
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    Re: Benchmark ABH2 Mono Block Consideration

    Technically, but semantics, it's still uses a switching power supply and weighs about 12 LBS. in a small chassis. Similar situation to my 5125 which is called Class V yet weighs 11 lbs. and produces 125x5.

    From your statement it sounds like the OP may benefit from auditioning an old fashion A/B amp.

    Quote Originally Posted by Dizzie View Post
    Quote is edited for brevity and emphasis.

    I am neither knocking nor promoting Class-D amplifiers. Not all Class-D amplifiers are equal. The same applies to all designs of amplifiers. Not all A, A/B, various tube designs, etc. amplifiers are equal. I only post the following from the Benchmark website to clarify comments some have made.

    My experience with Class-D amps has not been good but I keep trying because, and I repeat myself, not all Class-D amplifiers are equal. I have a new pair waiting for me to try when warm weather chases the tubes from my listening room.

    From the Benchmark website:

    The AHB2 is Not a Class-D Amplifier (And Here is Why)

    It seems like everyone is building class-D amplifiers, and some of them look very good on paper until you take a deeper dive into the specifications. Many class-D deficiencies are obscured by the fact that 20 kHz brick-wall filters are always used when measuring class-D amplifiers. These class-D test filters improve the measured performance, but they are not present when you connect a class-D amplifier to your speakers. Tweeters are not ideal low-pass filters and the class-D ultrasonic switching noise can produce audible effects when it interacts with the tweeters.

    Class-D amplifiers also suffer from poor THD performance at input frequencies above 1 kHz. Some of the newest Class-D amplifiers have impressive specifications at 1 kHz, when measured through a brick-wall 20 kHz lowpass filter, but this performance quickly degrades at higher audio input frequencies. It also degrades when driving low impedances and difficult reactive loads.

    For these reasons, Benchmark does not believe that class-D amplifiers are the best choice for reference-level performance. Nevertheless, class-D amplifiers are a great choice for cost-sensitive applications.
    Aurender ACS10 w/Audioquest Diamond USB, Esoteric N05xd
    Mark Levinson #526, 534 & JBL 4367's
    Clearaudio Performance DC w/Maestro cart
    Clarus Concerto & their Crimson cables

    HT: Marantz AV8003, Linn 5125, JBL SAM3ha, Revel s30,
    SVS PC13 Ultra
    Transparent, Analysis Plus & Tributaries. PS Audio filtering
    Sony XBR-75X940D & BDP
    Parasound P6, MBL 8006b, Artisan speakers/subwoofer

  10. #10
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    Re: Benchmark ABH2 Mono Block Consideration

    Quote Originally Posted by Mr Peabody View Post
    Benchmark, is Class D. So I wonder if you only post to push NAD which would be lucky to be a sideways move at best. You say the NAD would best the Benchmark but seem to have no knowledge of the amp you speak to best. Your NAD fanboy dribble is tiring. No matter what a person asks you want to find a way to insert your NAD story.
    The AHB2 is not Class D according to Benchmark - see

    The AHB2 - A Radical Approach to Audio Power Amplification - Benchmark Media Systems

    So no "sideways move". The OP was asking about the AHB2 (an amp I owned for 6 months) and for alternative amplifier suggestions. I answered his question as best and honestly as I could. The fact that the M33 that I currently own has been so highly reviewed by respected reviewers is surely no reason why it shouldn't be mentioned on this forum.

    Please see my response to the OP on the "other forum" to clarify how I think an amplifier should be chosen. No, tell you what, I'll copy it here -

    I've replied to your posting on "another forum" so won't repeat here.

    Only to add that changing speakers will make a massive difference to the rendition of music, whereas changing amp makes a much smaller, more subtle difference, This means that if you are not changing your speakers, you should home-audition a range of amps within your budget range to establish which sounds best to you.

    Don't be over-influenced by others' suggestions (even my own!), because they are not using the same speakers that you have. Also, in my view, take little note of quoted or reviewer-generated measurements. Modern amps are all pretty accurate and it's the unmeasurable "character" of the amp that has to gel with the character of your particular speakers. When you get this right, your music listening experience will be at its maximum enjoyment factor.


    I hope this may go some way to mitigate your anger at my post - it was not intended to be controversial. Thanks
    Sources - NAD M50.2 (streamer, CD player, CD ripper, hard drive music store)
    Amplification - NAD M33 all-in-one, NAD M12 preamp (in reserve), Atma-Sphere Class D monos
    Speakers - Avantgarde Duo XD, Avantgarde Duo (2006) - both aesthetically modified

  11. #11
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    Re: Benchmark ABH2 Mono Block Consideration

    Quote Originally Posted by Mr Peabody View Post
    Technically, but semantics, it's still uses a switching power supply and weighs about 12 LBS. in a small chassis. Similar situation to my 5125 which is called Class V yet weighs 11 lbs. and produces 125x5.

    From your statement it sounds like the OP may benefit from auditioning an old fashion A/B amp.
    That is not what I was implying. Please do not interpret my post to support your own bias. Do not lump every lightweight amp into Class-D. I did not recommend any amplifier topology. There is too much variation within each topology to generalize. I currently have three different topology monoblocs for my Sound Labs. I have Benchmark and Class-D amps which I won't name since I do not have enough burn in hours to evaluate them yet. My favorite monoblocs are the VAC Essence 80s tube amps. They only weigh 39 pounds and are small. Does that make them Class-D?
    Contributor to stereotimes.com

  12. #12
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    Re: Benchmark ABH2 Mono Block Consideration

    Whatever you say but the VAC amp is likely A/B and 39 LBS. is still 3 times as heavy as the Benchmark. What a futile attempt to make a point. A switching amp is still a switching amp. All some of these companies are doing is finding an alternate topology in order not to call themselves Class D due to the negative connotation that entails despite the cheerleaders.

    Interesting you choose to split hairs when you said in your prior post, "My experience with Class-D amps has not been good but I keep trying because, and I repeat myself, not all Class-D amplifiers are equal."

    Not exactly an endorsement of Class D either.
    Quote Originally Posted by Dizzie View Post
    That is not what I was implying. Please do not interpret my post to support your own bias. Do not lump every lightweight amp into Class-D. I did not recommend any amplifier topology. There is too much variation within each topology to generalize. I currently have three different topology monoblocs for my Sound Labs. I have Benchmark and Class-D amps which I won't name since I do not have enough burn in hours to evaluate them yet. My favorite monoblocs are the VAC Essence 80s tube amps. They only weigh 39 pounds and are small. Does that make them Class-D?
    Aurender ACS10 w/Audioquest Diamond USB, Esoteric N05xd
    Mark Levinson #526, 534 & JBL 4367's
    Clearaudio Performance DC w/Maestro cart
    Clarus Concerto & their Crimson cables

    HT: Marantz AV8003, Linn 5125, JBL SAM3ha, Revel s30,
    SVS PC13 Ultra
    Transparent, Analysis Plus & Tributaries. PS Audio filtering
    Sony XBR-75X940D & BDP
    Parasound P6, MBL 8006b, Artisan speakers/subwoofer

  13. #13
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    Re: Benchmark ABH2 Mono Block Consideration

    Hey guys I think the technology for amps is moving rapidly like DACs. I just posted another query about Gallium Nitride GaN Class D amps. Very excited about this technology to which I had not been paying much attention. Anyway I agree with what some have said here. Adding the second Benchmark is probably not going to satisfy me. I do like Pass and Bryston offerings. My problem is I really don't want a 50-90 lb amp anymore. Been there. The Bryston 3B Cubed is appealing at 35 lbs. But now that I've discovered these more advanced designed higher end Class D amps I will learn more about their advantages and disadvantages. Any way my new post explains more.

    Thanks for the responses and discussion. Always interesting to hear everyone's views and experiences.

  14. #14
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    Re: Benchmark ABH2 Mono Block Consideration

    Quote Originally Posted by JFRMusic View Post
    But now that I've discovered these more advanced designed higher end Class D amps I will learn more about their advantages and disadvantages. Any way my new post explains more.
    As I suggested elsewhere, don't worry about any particular technology and keep an open mind. Listen and decide on what you hear, not what you read or what others think about a particular technology. Some people refuse to consider Class D just because it used to be poor in its early days. I think these people may still be using film cameras and Betamax VCRs!

    PS - I think you're on the right track though. Good luck.
    Sources - NAD M50.2 (streamer, CD player, CD ripper, hard drive music store)
    Amplification - NAD M33 all-in-one, NAD M12 preamp (in reserve), Atma-Sphere Class D monos
    Speakers - Avantgarde Duo XD, Avantgarde Duo (2006) - both aesthetically modified

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Benchmark ABH2 Mono Block Consideration

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