As well as dirty power lines, the outside noise seriously effect the backround blackness of sound. This noise can not be heared directly so we don't mind so much but if you check with dB meter in the night and afternoon, it is really so much. Also, I compared many power cables and I made some myself, eventually I found a magic power cord, sidewinder (www.powersnakes.com) This cable makes unbelieve differency on smoothness and blackness of the soundstage, give a try you will seee immediately (You may order long and cut to two or three without any problem)
Different & inconsistent sound quality
I am noticing different sound quality from my audio system, depending on when I listen to them. My system consists of Krell integrated amp, B&W CDM 1SE, and Sony DVP-7700. They are connected with Transparent ML Super interconnect and MIT T2 Biwire speaker cable. For example, in the moring and very late night, piano recordings sound very clean, detailed, and transparent, however, in late afternoon or evening, it seems that some of piano notes from the same CD sound very dull and veiled. The phenomenon is true of other recordings of cello, violin, and etc. I suspect that AC noise has to do with the problem, so as a first step, I consider upgrading stock power cord for my integrated amp to a better one such as Transparent PowerLink Super or others. Could anyone help me with any possible solutions to the problem I'm experiencing? Any suggestions or comments would be greatly appreciated.