Hi guys, I was wondering if I could get some help / advise. I'm not really knowledgable about amplifiers at all (apart from what sounds I like!) so please bare with me as i'm sure the aficionados might facepalm. haha I recently fired up my Super 100JH for the first time since getting it. (sounds great by the way, prefer it to the 1959HW). But there is a buzzing that occurs when the amp is on. This doesn't happen when the amp is on standby, only when the amp is fully on. So my question is, is that normal? It's definitely not a hissing noise or a hum. Just a straight up buzz. It does it when there isn't a guitar cable connected to it either so it's not the cable or guitar. I don't remember experiencing buzzing with other plexi reissues i've had. although the buzzing does increase and decrease when adjusting the presence which is something I have experienced with similar amps. If it's normal then it doesn't bother me but I just want to make sure that the amplifier is functioning properly. Apologies in advance if this is a "stupid" question but I guess this forum is the best place to gain knowledge about this kind of stuff.