Perhaps what I ultimately want is unobtainable because more of one characteristic necessarily diminishes another. What I get from my speakers is a more dense sound--richer sounding harmonics and more beautiful tone, particularly for string instruments like the viola and cello. This thicker harmonic structure may be the product of the more resonant characteristics of the speaker. But, I also like the incredible clarity of the phones and the freedom from obvious resonant overhang.
I did some listening to some older, better sounding recordings last night. These phones really shine with richer sounding recordings, and sound particularly good with recordings which seemed to have excessive bass boom when heard on my speakers (Louis Armstrong/Duke Ellington collaboration). I do hear a lot of detail with these phones, both the good and the bad (dropouts and edits are a bit too easily discerned). Still, the bottom line is that they are completely enjoyable and I get wrapped up in the music and that is all that matters.
I have been a bit lazy about doing the tube substitution, but, I am in no hurry because I am still getting acclimated to the new amp (I think the more significant part of "break in" involves changes in the listener moreso than changes in the gear). I do know how significant a change in tubes can be to the sound. I have access to Mullard xf2s, Philips 6CA7 (friend's favorite in his amp) and some Telefunkens.