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.

@jfrmusic The watts are higher in mono but those watts cannot be used continuously (say 30 minutes) at 2 Ohm, which some speakers dip too. The single AHB2 can continuously drive a 2 Ohm speaker but at 190 watts (I think).

I see some posts above on the CODA. Let me chime in on this too.

I used a Benchmark LA4 on the CODA #8 and the CODA #16. They both are good with the #16 approaching great. The #8 lacks some clarity that I like with the #16 and AHB2.

Another amp that I like more than the #8 is the Sanders Magtech. I recently heard from someone with informed knowledge on this that CODA was involved in the design of that amp. The power supply is from Sanders. This amp, which I bought from Sanders used for $4k, is even better than the #8. I think it is the top end that is better than the #8. I love the Magtech on my Magnepan LRS+. The #16 is also great on the LRS+, but I use it elsewhere.

@zlone I am currently listening to the Schitt Mjolnir preamp (from 2023) with the Sanders and the LRS+. Great sound, a bit too warm for me for long term listening, I like the Holo Serene and Benchmark LA4 for long term preamp duties. The Mjolnir is a pure Class A preamp and a very nice unit. It is a 2-channel preamp and headphone amp, though the headphone amp does not work well with my funky RAAL CA-1a phone. Do not let the price fool you.

Schiit Audio: Audio Products Designed and Built in Texas and California

Edit: I am doing some testing on my office with the Holo Serene preamp and the Schitt Mjolnir. I cued up the Isley Brothers 3+3 on both preamps and for my ears the utter neutrally and clarity of the Serene wins over the warm Class A of the Mjolnir. The only thing the Serene lacks is a balance control. If I can make my off centre seating work without the balance control I am keeping the Serene with the Sanders. A great combo.

@zlone I was looking for the remote for the Mjolnir (though I do not need one). No wonder I could not find it.

The Holo Serene may work for you. It is a bit warmer than the LA4 but has all the other sonic attributes of the LA4. 

The Mjolnir is a much better sounding unit than the Freya+. The Freya+ was a fun listen but would not have worked long term for me.

@jfrmusic I made a decision today to buy a $10k set of headphones. Problem is I do not have $10k. However, I have a CODA #16 amp that can get me almost there money wise to buy the phones. I will be listening to phones more than the Livingroom system that has the CODA.

I have done extensive listening sessions with my Livingroom system and the CODA and AHB2. Infact, I wrote a thread about it here.

Audiogon Discussion Forum

This is what I feel needs to happen with the AHB2. It is not as strong on the bass as the CODA but on my new Yamaha NS5000 that is really not the case. On other speakers it was not as strong. I attribute that to the dips to 2 to 4 Ohm region.

The AHB2 can sound too hot on the mid and highs. I think that is an artifact of the upstream gear. I have a Benchmark DAC3B on my Livingroom system and it is too hot for the AHB2 (though not the CODA #16). A PlayBack Designs Dream DAC is a future buy and I think this solves the hotness issue. My much cheaper Musetec 005 DAC (sold) would likely also solve this issue on the Livingroom system.

When AHB2 amps are run in mono a speaker that does not dip too much into the 2 Ohm region should be used. My Yamaha NS5000 is likely one of those (I need to double check). One advantage of having monos in my setup would be that the AHB2 becomes even quieter. It also becomes louder by 4 or 6 dB at the same volume level as a single AHB2 (that is a big deal for me).

If you decided to sell your AHB2 and it is silver color give me a DM because I will likely go with monos after the headphone are sorted out. I already have silver a AHB2.

If anyone is curious this is the phone I will get.

(4) RAAL 1995 headphones, Magna and Immanis | Headphone Reviews and Discussion - Head-Fi.org

I am going to spend a few hours next week in Ventura, CA listening.

@jfrmusic I would be surprised if the MSB sounded better WITHOUT the HPA4. Does not make sense to add more gear and complicated the signal path but I always found the LA4 made DACs sound better.