I recommend Auralex bass traps in the corners and Auralex geofusors on the ceilings filled with rockwool or polyfil. I realize its a shop but the corners and ceiling are likely spots you can treat.
System upgrade
I am slowly moving forward with upgrading my shop system. I strictly stream. Yeah my shop is my listening room. Acoustical nightmare but still enjoyable. But anyway I recently got an ARC Ref5SE which I really do like. Have been eyeballing a VT-100 mkIII amp. I know it’s older stuff but I just don’t have an abundance of disposable income at this point.
I’m am focusing on system synergy. And also looking at a Ref150-SE, which is a little more than I want to invest at this point, but still in consideration. Not married to trying a tube amp, so SS is also an option. Appreciate any and all input. Thanks
Here’s my setup
Ref5SE
Auralic Altair
Carver TFM45
ENO
DH Labs
Canare 4s11
Forte III modified