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! 
phasemonger
As @dekay suggested, damping the piano strings (two per keyboard note---that's a lotta strings!) is the first order of business. They ring like crazy when provoked, much more than an acoustic guitar or drumset. A folded furniture moving blanket will work great.

Second should be replacing the Venetian blinds with either diffusion or absorption. Ideally, you want the left and right walls to be as alike as possible, so whatever you do to one side, do to the other. "Sweeten" the highs with Townshend Pods? Before acoustically treating the room?!
Thanks for the great input! I didn’t even consider the idea of the strings ringing sympathetically… that makes a lot of sense. And I know the two sides of the room are acoustically very different, so that could be part of the issue, too. 
I have the amp on BDR cones thanks to MC, which did wonders for the sound (really!), so I think I’ll work on the piano and room a little then revisit the amp. 
One thing to keep in mind is that you can often compensate for deficits in one side of the room by adding more to the other.

Of course, it's hard to get a good stereo image when your left and right are not balanced but if one side is too reflective and can't be fixed, such as with big bay windows you don't want to hide you can treat the opposite room with extra thick absorbers and diffusion.

And don't ever forget the ceiling.
You guys made me go check out my my piano, a 19th Century Mason-Hamlin upright. Anyway, the strings for the piano’s top eighteen keys are entirely undamped, and could conceivably resonate sympathetically. The strings for those keys, however, are under extreme tension. They did not respond one iota to my repeated shouts into the piano’s interior. In other words, I don’t think that, because it’s a musical instrument, the piano might be bolluxing up the stereo’s imaging. I do have to say, though, that any piano is a substantial piece of furniture, with a wealth of hard flat surfaces.