haha.. i oso have similar problem..
found out clip+/fuze not bringing out full details..
need a gmod..
then.. amp is a b****.. secret amp can drive proper.. but still got rooms to improve..
dunno what else can.. not to mention finding one that drives good... i like w1 better, but its soo underpowered that soundstage is still closed and crammed...
dunno what cable to pair with it too.. 
seems like need a really good amp to get it to fly.. cant seem to replicate the memory on at timesquare TT on how good the vtg sounds....
er.. wait.. this is senns thread..  should i go to my hd201 (needs to reassemble first.. )

yes, the HD650 does need a good amp to shine, the better the amp, the better it can perform. (but there's always a upper limit)

if you want similar performance, look at Shures SRH940, Denon D7000, MS-Pro, RS1 / RS2, DT770, DT880, DT990, AKG701/702 ...