But in any case, I'll see what it sounds like under the floor. I imagine that if I use Cara to work out room modes, and then when I measure I find something different, it may be because of the sub-floor space?

I have some other things to do as well - explore moving the piano to another part of the room to let the horns do their thing with fewer obstructions; put some kind of absorbent pad under the piano (a Jon Risch-style trap lying on the floor?); and then we'll see where I am.

The room needs to get back to the clean and minimalist look it had before I put all the stuff in there - it is meant to be a peaceful place, not just a listening room...