bigshot
Headphoneus Supremus
I wouldn't worry about it... too much. For IEMs, don't worry. For hi-fi speakers or full size audiophile headphones, it does matter a little.
Not in myexperience. I have a pretty fantastic stereo, and my media serveris all AAC 256 VBR. No need for lossless. Do a controlled test and you'll find out too.