Hi Gene,
Welcome to AC, it is a great learning place. Hope you decide to participate and offer your tidbits of knowledge in the AC pot of stew. Very nice system. You mentioned on 'gon that you love the ProAcs, well, you will literally
double their performance when you can hear them clearly after some acoustic treatments. It's amazing what the right treatments can do. But since you are a tube man, be careful not to harm that tubey transparent soundstaging by padding down the front wall area (behind the speakers). I use 8th nerve adapts in ceiling corners to good effect, they clean up the mids and level out the bass in my large room and although my wife complains since I have not painted them, she does allow them to stay. When painted they blend right in. You could make yourself some
homemade diffusors to cover that tile, just two or three leaned against it would be more than enough, but farther away from speakers would work better. A towel or some thin cloth is enough to break up the high reflectivity of the glass TV and tile so it sounds more like sheetrock or wood, still not perfect, but removeable in seconds for momma - maybe a thick flannel bedsheet? I don't really like the (lack of) sound of absorbors behind the speaker baffle line, but many people do as it tightens up the sound a lot, great for multitrack pop/rock music with canned reverb or synthetic soundstaging. Natural soundstaging like true stereo recordings of concert halls has more nuances that I think need to bounce out to fully bloom. I find that richness to be a little reduced with absorbers anywhere behind the speaks, but experimenting is the only way to know. Lots of great advice from Ethan, Bryan (bpape) and others here on AC. 6" thick bass traps leaning along the side wall starting right in front of the speaker improves bass very effectively for me, but WAF is highly dubious.

Congrats on a successful first system, Gene, now you will be hooked for life! All that research paid off for you.
Daverz, your post about attractive and unobtrusive got me laughing when I saw your CAT!

Great icon!