Experience with Simaudio Moon North amps

Simaudio hit the ball out of the park with the 791/761 combo. If you are in the beginning stages you might want to consider going with the naturally synergistic 791 or 891 with whatever amp you choose. I think the 761 and 861 are very similar, on paper (reading Simaudio Website) albeit more power on 861. If it were me I’d go with the larger stereo amp, the 861 and the 791 (or if funds permit the 891), strap that to your Sonus Faber and call it a day!  Two beautiful chassis’s and reference level  performance. 

I have had the 761 stereo amp for several weeks now; I’m pairing it with the 791. It’s powering Opera Callas Diva speakers (also handmade in Italy). I can’t say enough about this amp. I love it. I don’t see how you could go wrong with the partnering equipment you have listed. Octave preamp output impedance is low enough to not cause any problems with either Moon North amp. The clarity, dynamics, and reference level performance of the 761 or 891 will let your source components shine and very likely bring out the very best from Sonus Faber speakers. You may have to dial things in to your specific tastes with cables, but again I think you are on a good path. For what it’s worth, a single 761 in stereo mode packs a punch. It’s rated to 400 wpc continuous into 4 ohms. Assuming you have a massive room and like to play at party levels for wanting to consider mono blocks.
Happy Hunting!

@kerrybh My two cents: If your room is optimized acoustically, meaning optimal speaker / listening chair placement and (possibly) necessary acoustic treatment, like absorbers, diffusors, and bass traps you might benefit from the mono-block topology for theoretically increased soundstage/image. If you consider the crosstalk specs of the 761 or 861 stereo amps, both better than -115 dB, and superlative SNR figures, on paper at least, it begs the question of HOW can mono-blocks render different soundstage. The conventional 'wisdom' is that mono config might yield better soundstage but I doubt it would be night and day, and to unlock the full potential, all the other acoustic parameters should be addressed. Maybe it comes down to the extra current and power on tap, and that monos each work less, which possibly manifests a different stage. These days i'm aiming for simpler setups, hence a stereo amp. I am sure though either way you would be SUPER happy with the North Amps. 

@kerrybh sorry for delayed response.

Regarding my conclusion: it’s not a hard conclusion, more like a soft one, that is based on personal experience, accounts of other audio nuts, and guided intuition. The intuition part stems from the true dual mono design of the 761 and 861 amps; They pretty much are mono blocks in philosophy: they only share a chassis and a power input IEC socket. Each channel has its own well specified power transformer and related power supply components. The crosstalk (aka channel bleed) is ridiculously low, better than -115 dB on either amp. I don’t think it would be THAT aspect of such a design that manifests less capability to achieving a satisfying soundstage vs true mono blocks. I think the advantage of individual mono blocks is that of power. Dedicated monoblocks typically have more power reserves and depending on the speaker, may yield more separation as volume increases.

In a dual mono config like the 761 or 861 I think this gap would be pretty small, but in the realm of extreme audio performance, if that is the goal, then separate chassis and power cords (maybe even wall sockets because if they are plugged into the same socket then they are effectively strapped together at the same AC line feeder circuit) may be the way to go to audio nirvana. At some point the tradeoff just might not be worth it. Totally a personal decision.

There is another dimension to consider with stereo amps that can be switched to operate in ’monoblock’ mode: TONE and COHERENCE. I used to have a Luxman M-900U (had it many times actually, lol) and this was a pretty beefy stereo amp. It could be switched to operate in mono mode, and with another M-900 one could get massive power. I personally did not ever hear a setup with dual mono M-900’s but I have heard (from dealers and forum reviews) that the sweetness and coherence of the single stereo M900 is somewhat traded off for more balls and punch when in the mono config. In other words, the character of the amplifier changed. This is not to say that all mono amps present less coherence and potential "sweetness" it’s just something to think about, and it’s ultimately a function of the amplifier topology and the rest of the system. Make sure you listen to both options before doubling down on another chassis.
Happy Hunting

YYZ, did you side by side compare the 791 with Schitt and Holo or basing that off personal inference?

At the risk of derailing this amplifier thread to talk digital for a minute:

The 791 has more digital technology than just an ESS chip. There is a custom FPGA that handles clocking and other DSP functions. I don’t think it’s a fair call to assess any DAC by calling out the engineering choices on conversion technology (aka the DAC chip itself) a company makes. There are many factors to the final sound quality. Analog output stage, power supply design, layout topology, etc.

For what it’s worth on an internet forum, I have owned many high end dacs, one of which was a Bricasti M21 (for over a year). The M21 has the best implementation in the Bricasti lineup for the analog volume control. So it’s a 16K streamer, DAC, and preamp in one. The 791 is also a 16K streamer, DAC, phono stage, and preamp. It’s my opinion that both the 791 and M21 are top flight DACs and preamps and can be compared and contrasted fairly. I like them both a lot. There is system synergy b/t the amp and the 791 front end I think the only way to exceed its performance would be to add the external 820S power supply or move to the top tier 891 piece. Just one small opinion from a happy camper. Peace to all and enjoy the music!

Sounds good, thanks for the response. I’ve always wanted to hear a Yggi. I have a lot of respect for Mike Moffat. I remember years ago saving money to get the Theta Pro Prime DAC and used that baby for years. Moved up the Theta chain and always loved how dynamic and interesting they sounded. I’ve heard from others as well that the Yggis are a really great value and sound excellent. 

Interesting experiences above by other members. Synergy is key, as always. When I first received my 761 it was paired with Opera Loudspeakers, Diva Callas (latest version). The Divas are interesting speakers. Very capable, excellent separation of fine detail, very resolving. Over time with the 761 I played around with different cables and found the 761 to be very revealing of upstream gear and pretty much all ancillary equipment. It is NOT a forgiving, rounded golden amp. It is pretty much dead neutral, presents a super low noise floor, is very fast; hard to summarize in  a few words but it is an extremely highly capable amp. I am still learning more and more about music and tuning the system. 

Fast forward: a few weeks ago I auditioned ATC SC40 passives with the  641/681 and was so impressed and blown away by the organic synergy and overall performance I purchased the SCM40s. It's been a pretty short time since I have been listening to the 761/ATC pairing but I know synergy when I experience it. This is synergy like Luxman/ Harbeth, or Pass/Wilson. If you need more power for sure go with the larger amp, but do not expect the native character or "house sound" of the North series to be greatly different. I heard this with the 641 in my own house on the same opera speakers. The 761 had more control and more overall reach in to the stage and all that, but the colors and dynamics of the source were able to shine through in all the glory in either case. 
@kerrybh please update the thread if you get to hear the larger amp in your system!  Happy trails!

Zuesman that is great! Happy you love the 861 so much. I’m also smiling b/c that implies, by your calculations, the 761 beats amps in the 0.75 x 60,000 = 45,000 range ( it’s about 75% as good as the 861). I have never heard a 45k amp, much less had the opportunity to directly compare such amps in my specific system, so I can’t comment, but I can say the 761 is phenomenal across the board and has beautiful synergy with ATC. I also found that the 761 responds well with a DPS 4.1 power cable. Happy tunes!