Going against the grain here, but personally I wouldn't decide based on the opinions of other people's ears. Test some different files out for yourself, you may or may not perceive small differences between low and high bit rate MP3's and AAC's, and lossless FLAC, WAV etc. I personally see no reason to choose a lossy source, when lossless is available. That's my opinion and people will downvote me for it.
I pair my HD-650s with a Bottlehead Crack.
Going against the grain here, but personally I wouldn't decide based on the opinions of other people's ears. Test some different files out for yourself, you may or may not perceive small differences between low and high bit rate MP3's and AAC's, and lossless FLAC, WAV etc. I personally see no reason to choose a lossy source, when lossless is available. That's my opinion and people will downvote me for it.