ZakkSt

I recently managed to get myself a Mesa Boogie Basis M2000 for an absolutely ridiculous price. However it's obviously quite old as it hasnt been in production for some time, and i don't have much experience with Tube amps. When do i know when to replace the tubes and what tubes should i go for? Just as a side note. I got the Basis M2000 and a Mesa Boogie Powerhouse 1200 cab for the £500!!! Like i said, ridiculous price.