I started with some beats last year (yeah I know). Then moved up to the 20$ mono price MEP-839 Pro Headphones. Yes they were better than the beats. They were no loud enough especially watching youtube music videos. I ended up buying a little bear 12au7 amp that helped a ton. When there is no imput they sqeech sometimes. I have tried various ebay tubes but not much improvement. Switched all my MP3's to FLAC and that sounded even nicer.
All was good until I decided I wanted some real over the ear headphones. Found a deal on new dt990 600 ohm and got them in the other day. They sound great but anything over 50% the bass gets real washed out and muddy. The monoprice phones would boom like a bassed out lowrider (not saying that is my goal, just saying). Im not sure if my amp is not delivering enough power, the headphones are defective or I just want to listen to them too loud. Anyway I love the sound of acoustic guitar, and brass insterments on the dt 990's. I'm hating it that I cant even play ACDC thunderstruck at a decent volume to rock out without getting muddy bass.
Tips and suggestions all appreciated. Ohh and nice to meet you guys.. I tried to lurk for the last month but Im pretty much over my head
Some of those little tube amplifiers come with two Philips headed screws (right and left channel) for balancing and adjusting the voltage.
The testing and adjustments need to be done after the tube has fully warmed up, so it might have only gotten a "rough" adjustment at the factory.
Usually if your amp has them they would be right around in front of the tube (might need to remove top cover to see them).
The adjustment screws might be yellow colored.
Get the DT830 Digital Multi-meter ($6) for checking voltage levels.
Not sure on which spots you have to touch with the DT830 test leads to find voltage level
Might find some good info on these forums/threads.
You might have to up the volume on your source, so as to feed a stronger analog audio signal tho the Little Bear.
So turn the volume all the way down on the Little bear, turn up the volume on the source, then slowly up the volume control on the Little Bear.