If the HD535 sounds anything like the HD545, which it probably does since they use the same drivers and enclosure, then it is much better than HD497 based on a brief listen to HD497 at the Headroom show. The HD545 is very similar to HD580/600, albeit with thinner bass and slightly less detail. It is just as smooth with the same spacious soundstage and clarity. I saw a used HD545 for sale just this week, either here or at headwize for $50 -- it may still be available. HD545 vs. HD580 is very similar to a comparison of Grado SR-80 vs. Grado SR-225, with the more expensive model possessing slightly better details, soundstage and frequency extension.
A portable with good power can drive HD535 but that is not the ideal. I did enjoy my HD545 powered by 10mW and 15mW (into 32 ohms) cd players, but I don't really think of the HD545 as a portable headphone. For portable use I would sooner reach for Koss KSC-35.