Experience with Simaudio Moon North amps

I've only heard the 761 in stereo, two systems paired with the 791:

• Sonus Faber Amanti
• Wilson Watt Puppy

I have been impressed by the 761 - detail, finesse and dynamics.  Given the price difference between the 761 and 861 and the physical difference I would want to audition 861 in stereo versus 761 in mono.

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!

Thanks to you both. I used a moon 390 for several years and have a moon phono stage. I’ve been very pleased with simaudio products But have not had a chance to hear anything from the new north collection.

The primary reason I would consider mono is to maybe get a little improvement in the soundstage, but the amp certainly has plenty of power. Happy to hear the positive review.

@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. 

Thank you for that perspective. My room has been professionally treated, and I think it is set up reasonably well, although there are some factors that are hard to address.
I’ve never owned monoblocks so I don’t have firsthand knowledge, but have heard that monos would make a significant difference in soundstage which is an important factor for me. If the difference would not be significant, I would prefer the simplicity of a stereo amp  I would be interested in how you reach your conclusion if you don’t mind sharing. Again, thanks for your perspective.

@kerrybh I used to have a 390 - I think it's a wonderful unit.  I was shocked at the difference in sound when I swapped two M400s with for a 860A v2.  It's an upgrade in every way even though I went dual amps to a stereo amp.

I believe the 761 has similar characteristics with the 761 - I bet you will see a significant improvement. And just like the 860A v2, the 761 is a dual mono amp..   

@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

Thanks. All of that makes sense. I'm in the beginning stages of thinking about this, but like simaudio. Was thinking about dual 761s or a single 861. The 861 should certainly have more than enough power and I rarely listen at level above 85 dbl. Does the 861 incorporate improvements over the 761 other than having more power?

Thoughts on any of this are appreciated.

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. 

@kerrybh if 85 dBs is your typical listening level I believe the 791 will work extremely well for you.

Also consider the dimension of the amplifies - the 861 may not fit easily on your rack based on weight or dimensions.

Thing with the Sim amps is that Sim has stated in an interview that their amps were designed to be mono first and also support stereo. Sounds like a bit of marketing to potentially sell 2 mono amps vs 1 stereo.

I liked the 761 a lot and may buy it. I do not think the 791 was as good as my cheaper source chain. The 791 is super convenient and sounds really good but I think the price is a bit high. However, if I was advising a friend on a system, I would say to get the 761 and 791 combo over what I have. It is so convenient and has a high-quality sound.

My source setup.

- Optical streaming with a Sonore opticalRendu (much better than ANY Ethernet)

- Schitt Yggi+ OG (easy call over the ESS chip in the 791)

- Holo Audio Serene preamp is not perfect but as good as the 791 preamp section. 

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!

I did not compare my gear hooked up to a 761 against the 791. However, I have compared RJ45 streaming DACs against fibre optical and always preferred fibre. So, my preference there is based on prejudice for fibre. The dealer was not impressed by my view on this, but I am going by my ears.

I get what you are saying about the 791. It is an excellent overall unit. I just feel that a better volume control can be found in the super quiet Serene preamp (or Benchmark LA4/HPA4).

I did get a bit of fatigue on the Parasound Persona 9H system I heard the 761 and 791 on. Now I do not think it was the Moon gear, but it made me focus on the top end more than I expected. I think I get more detail out of the Yggi+.

With regards to the Yggi+ OG. I just have a huge appreciation of how great this thing is. It is much better than the $15k DAC that it replaced. It is super detailed without being fatiguing. It maybe is not the deepest soundstage but I do not care about that. I would love to connect the Yggi+ OG into the 791 via XLR and use fibre and do a head-to-head.  Fibre has never lost for my ears.

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. 

I just bought the Simaudio 861 amplifier upgrading from a SIM audio w8, The difference is unbelievable the amplifier is phenomenal It's about 25% better than the 761 and I have no doubt that this amplifier will go up against amplifiers in the 40 to $60,000 range from other companies and beat them, this is the first amplifier in the world that I know of that has no local or global feedback in the amplifier no other amplifier has that and there's no way I can go back to my w8 again even as good as it is.

FWIW I spent some time with the 791/761 combo at a dealer and my impression was similar to @yyzsantabarbara - 761 is stellar, 791 is very good but the DAC is a limiting factor. When I first heard the system I thought it was very good, but something was a little off and I suspected it was the DAC in the 791 - it had the slight forwardness, sibilance and uneven tonality that have bothered me in the past with 90% of DACs using ESS Sabre chips. Sure enough, switching to a DCS Lina with the external clock greatly improved things and I could really hear what the 761 was capable of. Given that the 791 preamp section was still being used with the DCS, obviously it is also excellent and the internal DAC is really the weak link. Obviously the Lina alone costs almost as much as the 791, and much more with the clock, so it's not a fair comparison at all. But it might be nice if you could get the 791 for a bit less money without the DAC.

I have the 891/861 combination, and the sound is completely amazing and cannot imagine a better sound from either the DAC/streamer using Roon (particularly with Roon through the MIND streamer which to my ears is more detailed than using a high-end USB cable into the 891’s USB input which is also excellent sound) or through my Rega Planar 10/Aphetta 3 combination through the Moon 810LP inputted into the 891. I have not tried the 891’s internal phono stage. The 891 DAC/streamer is upgraded from the one in the 791. There is a certain natural flow and detail to the music that is amazing and very lifelike and three dimensional, with excellent detail and bass, yet smooth, and makes one want to listen for hours. The pair retail for $47,000, and I think they are an excellent value relative to the cost of other high-end amp/streamer/DAC/pre-amp/phone pre-amp combinations where one could easily spend $100k or more. It is a certain flow state this pair creates that makes for an amazing sound.

Zuesman:

I am considering the 761 vs 861 at this time.  My dealer only has the 761.  You mention that the 861 is 25% better than the 791.  Please elaborate and explain the difference.

Trying the 761 (stereo mode) in my system, I particularly like the bass, separation of instruments, clarity and articulation.  The tonal quality of the bass and lower midrange seem very good.  As the frequency rises, the tonal character of the instruments seem to become harsher, brighter, especially instruments like violins. French horns sound more "brassy" and lose some of their "roundness" or "warmth" (vs other brass instruments). Note I am playing classical music. My preamp is a VAC Master, all my cables are Shunyata (sigma for power, omega for interconnects) and my speakers are Sonus Faber Il Cremonese-- so my system should be on the warmer, less clinical side.

I therefore am interested in knowing in particular if the tonal quality of the 861 is different from the 761.  If other sonic characteristics are also different that information would be appreciated.

Thank you for answering.  I appreciate your insight.

Thanks for asking the question Craig, I’m interested in that too. You have a very impressive system. I Auditioned the 761 in my system, Looking to improve on my Michii S5. I could not hear an improvement, certainly not one I would write the check for. I like simaudio equipment And was hoping this would be a keeper, but for me, it was not even though I’m sure it’s a fine amp. I keep trying to improve on what I have, but I think the Michi  maybe punches above its weight. I’d certainly be interested in the 861, however, if it is the kind of improvement described and would be very interested in the answer to your question from someone with experience.

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!

I will and I hope to hear the 861. I had a simaudio 390 in my system for a long time and currently use a simaudio phono stage. Simaudio builds good, high quality stuff. I’m a fan 

I have the SIM audio 861 and comparing it to the 761 everything is just that much better the separation, air and space between the instruments decay of the echo, the voice sounds more human and I think my estimation was wrong now that I've had it for a while I think it's even more than 25% better than the 761, because of the MDCA circuitry this is the only amp that I know of that has no local or global feedback and I believe that this amp will beat amps in the 40 to $60,000 range from any other company It's that good. Lookout Boulder and Gryphon.

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!