Ran the H-03 with the SRM-1, Mk 2. The Stax is a much more detail-rendering amplifier than the M-10, and really "wakes up" the H-03. The SR-507 sound very good with the SRM-1, Mk 2--way more detailed than the H-03 (which now sound veiled by comparison). The H-03 still have a more liquid/"tube-like" presentation with more bass weight/warmth/presence, compared to the SR-507. The KGSS DX is scheduled to arrive today and all I have on hand at the house are the KS H-03 (the SR-507 are at my apartment). Can't wait to hear the KGSS!