I have both for more than an year:I can't decide between Timeless AE and IE600. The sounding should be similar. Can anyone help ?
1/ ie600 is a V-shape but one of the best in industry; sparkle in the highs is quite a lot - not disturbing and tiring but noticeable; bass and subbass are very solid, no bleeding in the mids; for me it is a brighter Z1R w/o the huge soundstage; technicalities are close to high-end;
2/ Timeless AE is very balanced - it looks like V-shape but since it is a planar the bass and subbass are solid but less prominent vs ie600 (but still present); the mids, especially vocals are a bit more forward vs ie600, while the highs are just as perfect (no glare, no sharpness, no pain or distruction); sometimes the AE looks to me so balanced that is a bit dull (vs classic Timeless or vs ie600); on technicalities it is not on the level of ie600 but hits around $500;
3/ ie600 - cable is difficult to change (proprietary trick in the connection); so every time you need 3.5mm and you have installed balanced you have to swap the whole cable; while the AE has easy modular connections and scales-up with better cable more;
4/ it is strange but ie600 is so small that is not sitting tight in my ears while AE, with proper silicon or foam tips is always tight for long time
Hope I am useful. Cheers!