@jackd
To give you an idea of my system. I have a Sugden FBA800 Pure Class A amplifier, (neutral to warm, fast, and juicy sound), Audio Research LS28SE Preamp, Totaldac Triunity DAC, and Innuos Pulsar Streamer. The system overall tends to lean a little warmer, the Audio Research does add a nice splash of transparency to the system overall though. If changes are made, I can most certainly hear it, even if small.
My fear would be am I going to add more transparency to the system, which may not be bad thing, but I'd have to experience it to know for sure, and of course that requires buying the speakers. JMR is not a speaker you can go and listen to since they're in such short supply here in the US.
As far as room set up, yes I am locked into my seating poistion, but I can get the speakers 8 feet apart, thats about what I have my Cantabile at now. Off the back wall I can get about 20 inches or so, maybe a few more if needed but anymore than that I will be closing in on my seating area since I am only about 8-9 feet from the speakers themselves where I sit.
I've had Subs in the past, on the Bliss and also on a set of Wilson Tune Tots I had..I find them to be a pain in the arse to dial in but it's something I could do for infill if all else fails.