i would never pretend to try to do an audio review of listening devices because my hearing took a bad beating due to a lifetime of target shooting, 2-3 years on an aircraft carrier living 20' underneath the #2 catapult, and a sinus illness. i think most of the damage is to the high frequency hearing but when i get my massdrop sennheiser headphones in i can use a hi-res test album to get a map of which frequencies i have trouble with.
but, because the 300r has the balanced output, i was exploring some options to be able to use that and i discovered that pioneer sells some balanced earbuds which seem designed to match their daps:
https://www.pioneerelectronics.com/PUSA/Headphones/In-ear+&+Earbuds/SE-CH5BL-K
i haven't had more than a few hours of actual listening yet, but these earbuds seem to inflict no extra bass or coloration onto the music and are as comfortable as any other earbuds i've used over the years. the 'wire over the ears' is sort of awkward to me, but it's getting more natural the more i use them. they are compact and will tuck into small nooks in a pouch or pocket. i also got an adaptor which goes back the other way--balanced to unbalanced--which will let me use these on other audio devices. these adapters going either way seem way too expensive for what they are and the adaptor costs about 20-25% of the price of the earbud, but worth it so i don't have to carry a pair for the 300r and another for unbalanced players.
/guy