The comply tip are stil to small the cabels dont work good on my ipod for some reason but works good on everything else maybe thats why i had to turn it up so much. There still no distortion at max voilum. Defently more subbass but not by that much, sounds a bit fuller and there a littel bit of air and i notice a littel bit of sibilance not a big deal. before i never heard any. Thats the only diffrence that notice
The UE 900 did burn in as time went on for me. So your sonic issues with the signature may go away due to that. We aren't sure if the burn in is in the drivers or some other system, but the pinhole-nozzle proves to be very sensitive on its own (my claim is that this is what changes the sound with time; it gets clogged with earwax as you use it).
As for your volume issue, your iPod may be defective as you just isolated your iPod as the only source of issue. Get it checked out.