Benchmark AHB2 in Mono Block Configuration

@jfrmusic I know what I would do.  I would order the 2nd AHB2 and compare it to your single amp and see if you can tell a difference.  I would also get a home demo of the Bryston and demo it against the single and dual AHB2.   That is a perfect comparison scenario.  You may find that a single AHB2 is all you need or pick one of the other two options.

Have you adjusted the gain switch on the back of your AHB2 and can you tell a difference other than volume?  I think the middle position sounds the best - fuller with more body (even when adjusted to the same general volume) - than the lowest gain position.  I have read that technically it should sound the same so maybe it is just in my head.   

@jfrmusic 

You made the right decision on source equipment (end-game)! Now, you just need to put the icing on the cake. I would audition as many amps as you can, and don't just limit yourself to Bryston.

I wouldn’t necessarily categorize the Benchmark as a level below something like Bryston just because it is cheaper.  One way to look at it is those accurate electronics (I.e. Benchmark) will allow all the goodness from your front end to come through.  In all actuality, at that point the speakers would probably become the limiting factor.  But that’s ok if you like them - Harbeth can be magical for sure.  But as for the amps, I’ve owned both AHB2 monos and Bryston 2.5B3 Monos. The Bryston has a bit of a bump in the bottom end, whereas the Benchmarks are very flat. The Bryston has excellent bass, but also a bit more emphasis in that mid bass area. Again, you’d have to try it, but given the sound profile of Harbeth speakers which are slightly warm, I believe the Benchmark will be more synergistic.

The difficulty for me concerning many desirable Amps is many are very large and very heavy. Not sure if can handle a 75-80 pound amp by myself. Getting it home and setting it up. The Brystons are reasonable in weight. And of course the Benchmark is a feather weight.

If your speakers need a lot of power BUT are hard to drive a single AHB2 would be the way to go. Monos can sometimes be a little limp with very hard to drive speakers, such as the Thiel CS3.7. Some people with that combo like it but my experience was that when music called for a dynamic burst of power the AHB2 mono could not deliver it for the CS3.7.

My other amps handled those power demands much better. At that time my other amps were the CODA #8, KRELL DUO 175XD, and D-Sonic Class D (with Pascal module).  The KRELL and the AHB2 were my 2 fav sounding amps, but there were times when the AHB2 could not deliver.

I replaced the monos with a single AHB2 on the CS3.7 and it sounded a bit better, not a huge difference. The single AHB2 is rated for 2 Ohm while the monos can handle 2 Ohm on short bursts. At lower volume the AHB2 stereo was better on the CS3.7. 

Now my CS3.7 is a bit of an edge case and most speakers do not live in the 2 Ohm region. I currently have a 6 Ohm Yamaha NS5000 speaker that I use with a CODA #16 amp. I also have a AHB2 stereo amp that I occasionally switch too. It drives the NS5000 great. In this case, monos maybe even better since it does not go into the 2 Ohm region. I no longer have monos to test this out.

I owned a few Brystons, 4B ST, 7B SST, and the HPA-1 headphone amp. They all had a bit of hardness on top. I have not owned the 4B3 but when I heard it at a demo with Vandersteen Treo CT that hardness on top was still there but in a much-diminished capacity.

A few weeks ago, I had a friend over to hear my speakers. This guy knows his audio and is a professional in the audio business and former musician. We did a A/B test with the CODA #16 vs the AHB2 stereo. I think it was on the Stones Sympathy for the Devil track that the bass was preferred on the AHB2 over the CODA. On all the other tracks the bass was good on both.

On the Stones track my friend said the bass region was a bit confused sounding on the #16, but on the AHB2 it was perfect. I was rather shocked for 2 reasons, First the #16 is a bass monster and my prior experience with the Thiel and AHB2 did not ever consider the AHB2 to be strong on bass (accurate yes). The second thing that surprised me is that I knew my friend hated the AHB2 from his past experience. He still did not like the mid and top but I think a better DAC on my system would have solved that. The AHB2 is so revealing that any weak link in the system will stick out. The plan is for a future DAC upgrade.

For me the AHB2 mono beats Bryton as long as the speakers do not dip into the 2 Ohm region a lot.