Benchmark AHB2 in Mono Block Configuration

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.

OP, I have owned CODA amps, and previously had a Bryston 4B3. The Bryston was competent but that's not saying much IMO. CODA makes great value amps and currently I am running an S5.5 in my second system, a wonderful amp but perhaps not quite enough grunt for you unless your speakers are 88db or above.

As a few others have mentioned, given your new super-resolving source stack, don't skimp, get an amp from a next-level manufacturer like Gryphon, Esoteric, Block or T+A etcetera, otherwise you're not going to get everything your source stack has to give.

FYI I have a Gryphon Diablo 300 in my main system and it continues to wow me every time I run it - and especially when I run it HARD. It's like that girlfriend you once had way back when you were the Dude, the girl that the harder you went at it with, the louder/faster/BETTER it got.

I’ve owned many different Harbeths including the C 7. Have you ever considered using a tube amp? The combination of both is outstanding. I am using Quicksilver 70 watt mono amps with the Harbeth HL5.  50 watts minimum is sufficient with those Harbeths!

I agree with others you might want to add another brand there, +1 for Coda, a #8 would be a perfect fit. Not a big fan of bridged monos, though likely not an issue with those speakers. Depending on what kind of improvement you are seeking, I would not put Benchmark or, from what I have read, Bryston, in the category of warm sounding. I am currently looking to replace my LA4 preamp, it is just too clinical and lean sounding for me. 

Your budget is out of my league but I have been most impressed with Ayre Acoustics amps. I have compared them to Bryston and they consistently sound more grainless, transparent, and musical. This is the $12K stereo amp I am referencing. At 52lbs, it’s not a hernia machine either. VX 5-Twenty.