One way to figure this out is to lower the volume and see if you get less congestion. Or, use decent headphones with your system, and see how it sounds. If either of these reduces or eliminates the congestion, the issue is probably in your amp and/or speakers. If the congestion remains roughly the same, it may be your source components and/or preamp and/or AC power.
I am not enough of a Yes fan to test it for you, but a recent speaker upgrade determined that, in my system, the speakers were absolutely responsible for congestion at higher levels.
I am not enough of a Yes fan to test it for you, but a recent speaker upgrade determined that, in my system, the speakers were absolutely responsible for congestion at higher levels.