i'm considering getting this amp, where do you get your preamp tubes? i'm having a hard time finding these (from the MP website) - 6SJ7, 5693, 717A, 713A, 6SH7, 6SD7, 6J8P, 6*8
i noticed there are also 6N and 6L tubes that seem more available but not sure if they can also be used as they...