thanks for the reply matt -- It is a line6 amp. They make 1 amp with tubes that I know of... Yes, there are 4 tubes. The guys at guitar center say we should 'just replace all of them'. But, I'm not sure if they are giving me a line or not. The amp itself cost about 850 - and to get the 'better' tubes that last longer - they recommend the $60 X 4 tubes. I don't know -- I have to talk to my son to see what is up with it. But, once I get it - I'll take a look. This amp has a standby mode - which I believe it goes into first prior to shutdown etc.... They claim the stock tubes will go every 2-3 months...which is not something my jobless 15 year old son had counted on. The 'better' ones supposedly last 6 months - which still seems to be a bit ridiculous... My brother had an old tubed amp back in the 60's - and it NEVER blew a tube.... so is this typical of tube amps today - that they blow tubes every 3-6 months? He plays it - but, maybe 3 times a week @ 2hrs/time at most. He has another amp (marshall half stack) that he uses as well...So, the useage is split between the amps.