Monoblock suggestions to compare to SimAudio Moon Neo 400M?

I would avoid the Bryston 7B3 amps in your situation.  They are very nice amps, but they are just going to be too fast and thin sounding when compared to your preferred "Simaudio" sound.  Definitely a bad pairing for the Wilson's as well (which can be bright/harsh with the wrong electronics).

The SimAudio is definitely good stuff.  I think it has a sort of visceral grunt in the lower mids and midbass as well as a good depth of sound (ethereal you could say).  The closest amp that I remember hearing to this sonic signature are the Boulder amps.  You might like the new Krell and Levinson but they are much smoother and liquidy sounding in comparison to the dryer sounding SimAudio.

The PS Audio BHK is a very smooth amp, but it is slightly laid back.   I would say that it's very close to the ARC sound.

The JC1 amps are also very nice and very refined, but they are soft in the high frequencies.  I would say they are more natural sounding than the SimAudio, but they do not have that "midbass visceral grunt" or the high frequency extension that the SimAudio provides.

Somehow I think that amps designed to be mono would sound better than amps that are bridged to be mono.

Dedicated mono amps may or may not sound better than bridged-mono amps.  But one thing is for certain.  Bridged-mono amps will not be able to support lower impedance speakers as well.  The Benchmark indicates that it will support a 6 ohm load when bridge (which is really good), but many speakers will have impedances that drop down below 4 ohm in certain frequency areas.  It's never a good idea to buy a stereo amp "just to bridge it".

So, in the end, there are many good amps out there and there is no "best" amp.  It all depends on your "taste of sound", lol.

Actually, for those Wilsons, the Pass Labs amps might actually work out the best.  The Wilsons are a very dynamic speaker, sometimes overly dynamic and can sound too harsh/bright - the dynamics can easily get out of hand.  The Pass Labs have excellent resolution, but they are a very controlled sound and are just not as dynamic/exciting as other amps.  The Pass Labs will be much more neutral and realistic than the SimAudio.  The Pass Labs do not have that "visceral grunt" coloration of the SimAudio.

@auxinput - thank you for your responses.  Very insightful and a big help.  Really appreciate the time you took to reply.

The 400m are outstanding, I’ve used them with various speakers over the years and they are outstanding with a small form factor for a mono that I really appreciate.

My only issue, and I was actually going to ask in a new thread but Will piggy back here if okay is they are 36dB gain. Is that considered high? I can’t seem to find the gain on many amps but Sim does publish it.

The reason I ask is as we move more into room correction even for stereo I have a very difficult time with Dirac and these amps. I can almost never get Dirac within target no matter how low I set the volume-within reason. Same with a simple SPL meter.
I’m wondering if the 36dB gain is the culprit?

This has been my only issue but perhaps not for others.

Edit: I did just go to Bryston site and theirs are switchable 23 or 29dB so it looks the Sim might be a bit up there at 36. 

@dynguy The 36 dB of gain is higher than my other amps. How does this effect the sound, ignoring Dirac. Is the volume too high at a low preamp volume setting?