I have tried a few sets of tubes and have found good differences in bass response. My tubes from Kevin at Upscale were very thin and I was told to not spend a lot of money because they would not last long. I tried a pair of Amperex Bugle Boys(used and lasted 2 weeks)(local kid) and the bass improvement was amazing. That was my first clue and I knew I had to reproduce that or buy a new pre!! I later purchased Vandersteen 3a sig speakers and the seller threw in some standard Mullard tubes. The bass was still much improved relative to Upscale's. In another transaction with the same seller, I bought Mullard Gold Pins and that is my best to date. I highly recommend tube rolling!! I use my system an average of 3 hours a day and have been going strong for 3 months. My wife wants to add to my story by pointing out the greatly improved sweetness and soundstage!