[RockCity]

I actually have both cans, one the DT880 '03 250 Ohms and the other HD650. I was wondering if I'm the only one that has to turn the knob higher for the DT880 than for the HD650? I thought it would be the other way around because of the ohm configurations.

 

[El_Doug]

impedance isn't the only factor

the DT880's have a sensitivity of 96db, vs 103db for the HD650's

 

[glitch39]

Yes, the dt880 is less efficient than the 650. The 600 ohm 880 is even more inefficient.

 

[QQQ]

880(and 770\990)are considerably harder to drive than hd 650.
HD 650 actually easiest to drive high-impedance cans.

 

[Uncle Erik]

It also depends on how well the output impedance of your amp matches with the headphones.