It's quite possible you just don't like the HD800. The try Anax mod on the HD800 first and go from there
I have seen a blog on HD800 Anax mod but it seems to me that it improves several aspects of HD800 and
that probably save us from expensive cable. I do use the Zeus Gold clad Aphrodite cable which do improve
some of the sound to the one I like. However I would like to know how can you improve it more with the BA
and possible tube rolling. I don't like the modification on the headphone because it may destroy its value later.
It's not permanent. Comes right off w/ little or no residue if you use the right foam.
I know I haven't answered your tube selection question yet, I'm waiting for the production S7 to roll tubes in for verification. Whatever I say now could just be blowing smoke. Plus even then, the individual tubes can and will likely vary within makes and models as you know.