[Reck45]

Seriously what the heck is up with that? I was just using an onyko receiever and at 20% volume the 555s were at normal volume. To get the same volume with the 497s I had to set it at 40%? Very odd...the 555s are easiser to drive but at the same time they're not...

I never realized how dry and boring the 497s were (even amped), but man when I first got them I was blown away hehe. Yea but I guess the truth of it is like you guys said before I'm bored with music, I realize that now. I'm just not impressed with the 555s or the 497s anymore(which originally I said I preferred over the 555s). Which is probably a sign of over doing it...I listen to music a hell of a lot. Think I'll take a long break...

 

[Eagle_Driver]

Your problem with loudness there is the effects of output impedance. Most receiver headphone jacks have an output impedance in the hundreds of Ohms. And if the headphone's impedance is too far away from that output impedance rating in either direction, the output will drop significantly. Therefore, my best guess is that the HD555 is much closer to the jack's impedance than the HD497.