yeah, I will try switching out the tubes, though i hope i haven't burnt the the siemens CCa's I have in there this quickly. I would love to locate a former melos employee and have been in touch with audio horizons about more extensive modifications including a stepped attenuator, upgraded caps and a power supply that would be in a separate chassis that's just a little outta my budget at the time. If one tube has been burning harder for longer will it die quicker? and will the channel associated with that tube have a weaker output as its days come to a close? This is actually my 1st piece of tube equipment so there's still plenty i dont know.