I listened to the stock quickie for about 80 hours before changing the tubes to some 50's RCA. This dramatically reduced the microphonics of the preamp. I then racked up about another 40 hours before installing a pair of auricaps. Initially upon installation, the sound was constrained and rather lifeless, albeit with slightly less fatigue than the stock caps. After about 8 hours, the sound opened up a little, and the bass started to tighten up. After about 30 hrs on the caps, the sound was very dynamic, and the soundstage had opened up a lot. The caps are a huge improvement over stock, and I highly recommend splurging on a pair. (I spent $12 a piece at partsconnexion.com) The final change I have made to the quickie was rolling in a pair of amperex tubes that I bcought at tubeworld. c Another drastic impcrovement that I canncot recommend enough. ($25) I am very happy with how this thing turned out... now an astonishing little device.