What about the Empyrean with a PrimaLuna? (no one asks?)
They are amazing! I personally didn't expect much of a jump from my mj2 and 1960 siemens tubes.. but there it was. The PL almost makes me love these headphones.
That said, do stick with the EL34 tubes (which are the stock) - i just put some KT150 tubes in, holy cow do they sound amazing! - but, those tubes are pushing really close to bass becoming boomy with the Meze (not my other headsets or speakers.) So a warning if you plan on getting a PL, using the empyrean and want to use KT150s. It is right there at the line. But, one could counter act it with some 12UA7s in the gain tubes. Maybe Not the Brimar CV4003 (which i'm using and LOVE... but with the Utopia.)
also, random tube pr0n: