The 348A's are not plentiful, sadly. Have talked with someone who owns these and was told that the 350B is the special sauce - normal 5U4G's and 6J7's are sufficient.Sweet amp, how plentiful are the 348A tubes? Looks like maybe some microphone input transformers on the far end?
I know I'm beyond lucky to find a single one of these to begin with. What's luckier is that this came equipped with two input transformers - the 618A and 618C.