Headphone impedances and such

[sile2001]

Ok, so I guess there's something I still don't quite understand about impedance or maybe it's something totally different. For all of the tracking I do, I have a pair of Sennheiser HD280's (64Ω impedance) and two pair of Audio-Technica ATH-M40fs (60Ω ) cans. When I plug them into my iPod, they sound like total crap. No clarity, no depth to the bass, and absolutely nothing like they do when being driven by my headphone amp. On the other hand, whenever I use my cheapie Sony earphones (24Ω ) or my Koss KSC-50 earphones (64Ω ), it sounds great. What gives?

 

[mshilarious]

Ok, so I guess there's something I still don't quite understand about impedance or maybe it's something totally different. For all of the tracking I do, I have a pair of Sennheiser HD280's (64Ω impedance) and two pair of Audio-Technica ATH-M40fs (60Ω ) cans. When I plug them into my iPod, they sound like total crap. No clarity, no depth to the bass, and absolutely nothing like they do when being driven by my headphone amp. On the other hand, whenever I use my cheapie Sony earphones (24Ω ) or my Koss KSC-50 earphones (64Ω ), it sounds great. What gives?

What about the sensivity rating of the headphones? Also the impedance ratings are nominal, if you looked at the impedance curve it might illuminate matters. I'm guessing the iPod just doesn't have enough juice.