I called to order a epicenter today. The rep gave me some story about how it only works with music 20 years old. So I called Audio Control to ask. The rep there said that it was true in a way. That it didn't help store bought CD's , but it made a huge difference on music that had been converted to mp3 format. That when the file is compressed it sacrifices the integrity of the bass signal.
I don't know how an epiccenter works, but mp3 works by cutting out sound that most people can't hear. As you lower the bitrate it starts distort the sound that you can hear, and sounds bad.
So yes, music loses dynamics when compressed to mp3. Wether you can hear the difference between a good quality mp3 and the original is debateable.
Along with alot of other info as well. Mp3's are good for what they were intended-a preview. True high quality musical reproduction and Mp3's shouldn't be in the same sentence.
A lot of people find mp3 to be good enough for daily listening. You really just have to listen to the same music in mp3 and original CD on the same stereo to see if you can tell the difference.