There's been a lot of controversy about whether amps "break in" and get better-sounding over time by playing them. I'm of the opinion that they do, based on my own experience. I ALSO think it's true that experience with an amp allows you to tailor the settings better to your own idea of what its tone should be, so that's a definite factor, but in my case, I use lots of different settings in the studio to get different kinds of sounds because I only have one amp. So I'm ALWAYS turning knobs. I'm not a "set it and forget it" kind of guy, so I'm going to have to discount the notion that I just tweak the darn thing until I like it and simply get better at dialing it in to one particular sound. Last night I had the pleasure of hanging with Scott Peterson, and wanted him to check out the TR Onyx Sig head I got over the winter. I'd been using the amp a lot, especially for recording, but hadn't really cranked it in a while. I record at moderate volumes. I wanted Scott to hear how it sounds at gig levels, so I cranked it a bit, and damned if it didn't sound BETTER than I remembered it ever sounding. And I loved it before! It was juicier, it was sweeter, more open, etc. etc. etc. In all honesty, it was simply more better. In fact, my experience with this model (Onyx) is that this break-in thing really gets noticeable after about 6-8 months. The one I had before also really sweetened up after I had it for around this length of time. Now, this could simply be attributed to the fact that memory often fades, and to a whole bunch of psychoacoustic phenomena, but I'm going to stand by this opinion: as the amp is used, something happens to make it sound better. I don't know what it is, and I don't really CARE what it is, technically, but I'm pretty darn sure it's really there. I'm also sure it isn't the power, because my studio's outlets are all wired to a 2kVA Sola isolation transformer that puts out a VERY steady and clean 117 volts. I think it's one reason why people have such a deep love for vintage amps. They really DO sound better with age (assuming they work properly). So I'm not saying that this is only true for one brand of amps (though I've not experienced it to this degree so quickly before I got into TRs). I will fully agree with anyone who says I'm nuts, because that's kind of a given, but I think amps break in.