Hassle free tube amp David Berning ZH-270, tube life is an estimated 20 years and biasing is done automatically on a cycle by cycle basis. The tube life was not a concern but more a bonus, I purchased the amp for its superb sonics.
I use a tube pre as well and the tubes in there last a long time anyway, maybe a few years.
I use a tube pre as well and the tubes in there last a long time anyway, maybe a few years.