I recently replaced my power tubes in my DC3 with a set of JJ's... and still had an initial problem with my amp.. (see previous posts "DC3 problems"..)... maybe i got a bad one from my new batch.. put a spare mesa tube to replace the socket/tube that was acting up, and no more problems.. of course it's probably delivering the same sonic value as riding your car with an odd tire... I am thinking about doing a complete "oil change"... Eurotubes has a pretty good deal on all tubes for around $85... and they let u specify if u want "early, breakup" middle of the road break up, etc. for your tubes.. depending on what style u play.. they use JJ's.. anyone have experience with this company??