One bit of potential help; the power amp sits underneath a gorgeous cabinet. Perhaps you have already checked how hot the amp gets in that tight location. If the amp runs hotter due to less air circulation it can effect the life of the amp. It's nice to have things hidden, but not worth shortening the lifespan. I also would not be excited about the heat radiating up against the beautiful antique, as over time it could cause the wood to dry severely. Perhaps that is overly-cautious, but a thought for you.
When we were in our former home I also had similar blinds to close when listening. It worked well enough, though it was at the listening position rather than behind the speakers. One has to accommodate real world conditions!
Again, kudos on a lovely room and audio setup!