You already have the best headphone for Tube amp listening IMO. I have put my 6xx up against my 800s and Fostex TR-X00 and other assorted dynamic headphones from my collection and none quite reached that same level of depth and warmth while maintaining its clarity and separation. I picked up a custom XLR cable for it, rolled my tubes and will say without hesitation that it just does not get any better than what I hear every time I turn it on. With that said, I will add that in order for me to get the sound I like, I have to play Flac files. Also, let me say that I do have compromised hearing so that may be why I find it to be a better sound than the 800s which doesn't seem as warm and quite a bit more analytical than the 6xx.