***UPDATE: OK1 vs Stax SR-003***
For this comparison I used the OK1 amped with the Headsix, and the SR-003 amped with the SRM-Xh. The Xh is a vintage amp that should be better than the stock, portable SRM-001 that comes with the portable babystax, but not as good as the SRM-252 that comes with the Stax SRS-005A package.
The Headsix pairs especially well with the OK1 with its lush, warmish but very detailed sound.
The OK1 are dry, while the SR-003 are warmer, romantic, seductive, like a sunset and a red painted sky. The SR-003 are very colored, but in a very pleasant way. I prefer the SR-003 color over grado sound signature the PK1 have. The OK1 tend to add less to the music, and to let it flow freely. Both have very good soundstage and separation, but the SR-003 are in another league compared to everything else I heard. The SR-003 are electrostatic, and that's interesting how they are very detailed with a dark sound, ie no boost in the upper mids and treble (like Etymotic do). At this point, we don't need to describe the sound signature of the OK1 any further. The SR-003, instead, have an emphasis in the midbass and lower mids. The overall tone is very pleasing, but I could use less midbass. The lower treble on the Stax is perfect, slightly subdued to control sibilance, but not muted like it is with the RE1. The Yuins can be a little brash with the harshest recordings. The stax have rolled off extremes. The OK1 have more extended highs. Both the SR-003 and the RE1 lack the deepest bass. The Stax are enveloping, seductive, romantic. The OK1 are neutral, less "fun", more analytical/uncolored.
Being the Stax more resolving they make me aware of the any kind of imperfections in the track (like artifacts). This is a downside for casual listening. These artifacts can still be noticed with the OK1, but you don't feel like you are spotting them, one by one.
I prefer the Stax (pretty much to everything I have heard), but I rate both very highly: they are so different to be complementary, and I consider them to be the two single best earphones I have tried so far (I haven't listened to the UE11).
As a guess, I think the OK1 could do really well with the Lisa III and its bass knob (so that anyone could tailor the bass at his own will), or a beautiful tube amp.
The SR-003 (or the SR-001) could do a better with Audiocats modded SRM-001 (portable amp), or with the SRM-1 MkII and the SRM-313 (home stationary amps).
