@devilboy I critique as I listen. Well 90% of the time. Some music, depending on the source will sound different. for example, my vinyl music definitely sounds different to my streamed music. I and very focussed on vinyl, more than likely because of the constant attention it needs, whereas streaming is just that.
My point is that the system in essence stays the same, but the source changes the music quality. I do not expect that my system will sound appreciably different if I went on a spending spree and upgraded my interconnects or speaker cable for a few thousand.
If I spent that on component upgrades, I would most likely hear a qualitative improvement.
My "unqualified" opinion, in that I am not qualified by way of in depth theory or extensive listening of a huge number of different cable combinations, is based on my own system and the numerous friends and HiFi listening rooms. To this time, and I haven't achieved "nirvana", I don't see the immediate need to rewire my system at exorbitant cost.
Having said that, I cannot dispute that some listeners appreciate the change in the way a system sounds after changing (a) cables. That is their fair and right opinion.