I have a TSL and noticed that if I turn the amp on before letting the tubes get hot I get a horrible white noise that won't go away and results in no output from the guitar....just a waterfall water sound and nothing else. On the other hand, if I let the tubes warm up for 4-5 minutes before taking the amp off standby I have no problems whatsoever....great tone, no problems, everything is perfect. The tubes are the problem...already swapped them. It really isn't even an issue as long as I wait a few minutes for the tubes to get hot before I start playing. I this normal? Is that just how long it takes or is something wrong with my amp?