Acoustic treatment for windows and a piano

Hello all,

This is my first question after much lurking and a few thread replies. I appreciate everyone who contributes to this community - I’ve learned a lot from you. 

My listening room is 13.5’ wide and 16’ long. On the left side wall I have an upright piano (hard surfaces, reflective), with some acoustic tiles above the piano to dampen reflection. I have a big rug covering most of the hardwood floor, with a thick pad under it. The ceiling is typical bare drywall.  

On the right side wall I have two large glass windows, two separate window cases. I have typical wood Venetian blinds on each window section. 

My problem: Despite a lot of tweaking and positioning, my highs have amazing clarity but are still a bit harsh and fatiguing. I’m thinking I need to treat the windows, it’s likely I’m getting a lot of reflection off them and the hard wood blinds - but maybe the piano is a problem, too, or maybe I’ve reached the limits of my gear. 

Key system points: Rega RP8 TT with Hana SL; Tavish Vintage tube phono pre; Rega Elex-R integrated; Martin Logan Motion 40i speakers. I have good quality interconnects and speaker cable, and I have some sort of vibration control on every component. 

My questions:

1. Is the piano likely part of the problem? If so can I do anything with it? It’s a very nice piano that I play daily so it’s not going anywhere, and I really can’t rearrange the room due to layout. 

2. Are the windows likely part of the problem? If so, would you recommend drapes, acoustic blinds, or something else?

3. As I’ve improved my system, I’ve begun to suspect the amp is maxed out for sound quality. It feels like the speakers could give me a bit more with a better amp. Is it possible the harsh highs are from the amp alone? I’ve read the Elex-R amps can be lean in the highs, and that’s exactly what I’m experiencing. 

Thank you for any thoughts!