I have been thinking about trying an impdance adapter out with the 225. The only reason I haven't yet is that I can't find one that's 1/4" to 1/4". I really would rather not have an 1/4" to 1/8" adapter, then a impedance adapter on top of that. That might be kind of silly I know StanD's recommendation of an LPAD sounds like a better solution, but I have not been able to find one any were on the net that is suitable for use with headphones.
It takes only two resistors per channel to make an L-PAD that will attenuate the signal and keep a low enough impedance to damp the headphones. Four resistors, two jacks, a box and some wire and you can make one. Or else you have to find someone nearby that can solder.
I figured out the resistors for someone a few days ago. If you match the resistors on a meter you can prevent any imbalance in the channels.This was for a specific set of headphones.
At what position do you have the volume knob when you listen with the SR225i's?