Do you guys have to turn up the volume a bit when you play MP3s? I noticed that the output on non-compressed files play lounder and cleaner than MP3s but I want to be sure that it's not just my system. I get considerably less bass on some MP3s than I do on wavs/regular CDs. The mids and highs differ by volume a bit, but the bass is much lower on some MP3s. I have to turn up the bass on my HU to +5 or more and turn the cross over to max whereas on regular CDs I'm at 0 on HU and -3 on crossover. Is this normal to varie this much?