Like it....
I see quite a few stories about people buying-selling-buying again. I have done that with 580's (on my 3rd pair), 600's and 650's (twice each, still have a 600 now, thank-you-Nate).
Indeed, tube amps help, as one of my favorite budget "fun" combo's is the Eddie Current Lunchbox and 580. Got that combo again now.
Good balanced amps seem to also have made a difference in perception of the Senn's. I remember seeing stories of how that mystical veil disappeared with a good balanced amp. Tyll's description of the 650 acknowledges that veiled may be valid as a descriptor; I'm not so sure, but maybe it's just semantics....if an amp can "remove" it, not so sure I'd want to call it a veil....but minor quibble....
So good one, Tyll, a nice read about nice phones.