Thanks. I listened to the TH600 at a meet and for whatever reason wasn't taken by it. Might have been source or amp pairing or whatever. The 900 was exciting by comparison. Is the 610 a distinct variant? It's one thing I love about this hobby - chasing the ultimate. YMMV and all that. For example, I like the HD600 more than the HD650 Senn. Both good. My best "value" pick remains the very reasonable Goldring DR150. I love that model and bought a second pair. Thanks very much for the input!