...my room is (...) is full of glass windows.
It sounds like there's not a whole "damnation" of a lot you can do about room treatment (heavy velvet curtains @ 1st reflection points??? Even that might only work over ~5kHz or so).
Rather than strain the purse with expensive h/ware upgrades (at yr level, "better" would mean giga$), why not play with the following cheaper "passe-temps":
-DIY power cables
-A transformer coupled volume control -- disconnect the pre(diyhifisupply in HK has a good one)
-Try power amp plugged directly into wall socket (then, pre+power)
If you DO consider there is significantly more to be had from yr (excellent) system than you're getting, I would try a different pair of (94+db sensitive) spkrs. Obviously not at home, as you note -- but @ a dealer???