Yes. I once had lots of cardboard boxes stacked around my listening room, during a house remodel. That made my M60s sound great, esp vivid stereo imaging. When I removed the boxes, it didn't sound as good. I'll be putting some acoustic panels on the primary side wall reflection points to fix that.

It's funny people get engrossed in whether in some speaker cables, amps, and interconnects sound better than another, when the room acoustics makes a far bigger difference.