This turned out to be a surprise. I was starting to get worried my amp need a filter cap change as I was getting a strange, ugly out of tune distortion spoiling the attack of strong clear notes. A compressor just made it worse. I cycled a few guitars and found it was really just the one single coil guitar that did it. Snipped the treble bleed I'd put in a while back. Now it is perfect and the sounds are crystal clear. It is not an effect of treble bleed circuits that I had seen mentioned and I had assumed guitar voltage and current levels would not effect a cap like this. Anyone else experienced similar?