Ok guys. I need a little input. Yesterday I had my 508ia all day (I work where I listen). Last night I went to my kitchen to grab some food and when I came back to my office the amp was buzzing really loud through the speakers (I think both, but I turned it off pretty quickly before I checked for sure) and the volume control made no difference - I could turn it all the way down and the loud buzz was still there. The other thing of note was that the 300B on the right hand side was glowing pretty purple. I turned it all off and tried turning it on an hour or so later and the buzz was still there (forget to check if it was in both channels). After sending a couple emails out last night I realized I should find out if it's both channels or just one - maybe it doesn't matter - I don't know. This morning I turn it on and it's all working fine. No noise. Sounds great playing music. Does this seem like a tube issue? It does to me, but before I drop some money on some new 300B's I'd love to get a couple opinions. I don't have a LM dealer near me, so worse comes to worst I'd be taking it to a tech at a local shop that has worked on stuff before. But if this seems like normal bad tube behavior I'd rather just order tubes.