Just because it has been said many times doesn't make it true. Way too much BS around "properly driven". "Loud doesn't necessarily mean properly driven?" What does it mean then? Please explain how an amp can drive a headphone to loud, but a more powerful amp is needed to drive it "properly"? Apart from a different sound signature (IE distortion) how does more power (over louder than necessary) "improve" the sound, and if that is the case won't every headphone sound better using an amp with more power?
Volume will make a difference as to how we perceive the sound signature, but volume match an adequately driven headphone with a considerably more powerful amp, and difference will come down to (sound variation) added/less distortion, which won't always go the way of more power, it will favour amp design and materials, and subjective listener preferences.
I have a desktop amp that could blow Diana up, and it sounds great, but Diana also sounds great straight from an A&K SR15.
Unnecessarily powerful amps, expensive DACS, $1400 superconductor cables LOL; expectation bias.
Chimney189, your Diana will sound brilliant from the A&K Kahn cube. Those that say there is no low end, lacking bass, must be comparing the sound to a fart cannon. I am not sure if some of the people on Head fi have ever heard live music, that is a benchmark, not a Sony MDR XB1000 extra bass.