How should I treat window behind listening chair?

Heavy honeycomb cellular shades is a reasonable compromise in many cases.

Rives -

Any chance the BLACKOUT material INSIDE some of the cellular shades helps versus non blackout material shades? Just ordered some and had wondered this.....

Thanks
Dan

I have drapes on 3 of the four walls of my listening room because it's a very small room and had annoying slap echo (clap your hands and hear it ring). I find the drapes hugely improve the sound.

However if your system sounds dull and lacking in treble detail the drapes will make it more so, as they affect high frequencies proportionally more.

Blackout has less, considerably less absorption coefficient due to the black out foil, however, the foil does create some diffusion. So it's not really a one is better vs the other, it depends on the room and placement.

Marigo Labs makes VTS tuning dots to attach in proximity to corners of windows, as well as other types for every part of a system, and room.
Can check the website, marigoaudio.com
Also, can email Ron Hedrich at the website. He creates the Marigo Labs products.