This is a very highly touted MV on forums but after a couple of years of having the PPIMV in my amp I've decided it just isn't for me and pulled it. Here's the issue. The volume reduction at a usable tone isn't substantial. Yes it can be dialed way down to zero but the lack of NFB dramatically changes the character of the amp. Yes there is all kinds of distortion happening at low volumes, but it isn't "good" distortion and the amp will not clean up. Now, this was a well thought out and well executed installation. I spent hours and hours reading pages at the metroamp forum, where this implementation was essentially born (ya, I know about the ken fisher connection) and I used a top of the line PEC pot like george recommended, my lead dress was well done, tightly twisted wires - no noise or occilation. I have tried several nfb resistors and installed a pot too (as seen in pic). Still no good at low volumes. Put in a bigger fizz cap, helped a little but still no good. So in my case, at best this MV is good for trimming a few db at band levels. That being the case I installed a pre-pimv and cascaded my preamp for more natural tube break up and I have been happy as a pig in sh!t ever since.