i just finished retubing and biasing my DSL 201. This my was first ever attempt at biasing and I have some questions. I let the amp warm up for several minutes before attempting to bias. I set one side for 550mv, then went to set the other side. When I set the other side I got more fluctuations on the meter. It would sit at 550, then run down as low as 546 and then come up over 550. I kept working both sides to try to get them as close to 550 as possible. When I let the amp sit idle for a few minutes I would see the numbers randomly drift again. What’s weird (to me at least) is that both sides seemed to stay with each other when I would check them. At one point I put the amp on standby for a minute and then turned it back on. The meter then read 574mv. Is this behavior normal or do I have a bias drift issue? I wish I could be more descriptive, this was my first attempt at ever doing this. On a side note, the amp seems to work fine and sounds good - although I didn’t want to play it too long and push my luck. My goal was to warm the amp up, set bias, then let the amp sit and recheck 20 minutes later or so and reset again if necessary. But, the numbers seem to move around a lot and not remain static. Any thoughts? It’s going to a tech next week, but I thought I would get a jump on things (and try to learn something).