Oooh, I would love to hear this combo when you are done. I think the McCormack would pair very nicely with the tubed pre and the Cremona's.
Hi, I hope that I'm not imposing, but I wanted to provide you with an additional path concerning the Herron versus the McCormack.
I had the Herron VTSP 1A/166 and the Herron M150 monoblocks that worked really well together and was very, very musical. I had my system in a 14 X 30 room with cathedral ceiling. Unfortunately it wasn't enough power to push the speakers to satisfactorily fill the room (my music preference seems to be a lot like yours). I moved it to a 10 X 12 room with 8' ceiling and it was fine.
A year and a half ago I replaced my Herron pieces with a Karan KA I-180 integrated amp, which is quite a considerable upgrade in my opinion and is also a tad bit warmer while being much more detailed. The Karan also grabs a hold of the speakers and controls them like a 'Class A' amplifier, but doesn't run hot like they do. I moved the system back into the big room and can now fill it with no problem what-so-ever.
If you don't have any objection, which many people do, to an integrated amp, the cost from only needing one power cord compared to three power cords and one set of interconnects also saves a lot of money.
Of course you have to weigh that against not having a separate preamp and amp and those limitations if you lean towards upgrading very often.
You can check out my system, the first picture is with my Herron pieces in the smaller room.