Hi there,
let me comment bit rates issue, if y'all don't mind..

so, our files are encoded at constant bitrates as well as at variable ones. bitrate can be always found under the blue "download" icon.
if bitrate is "192 kbps" or "320 kbps" then you can obviously expect the file with the specifed bitrate.
When you see VBR under the icon - this means that track is encoded at variable bitrate. i must clarify that 90 per cent of our VBR tracks are pure and up to original sound. Why is it VBR? simply - this is best encoding method for quality/file_size relation.

please read more at our help section, there's clarification what is VBR.
yes, we receive low-quality tracks time from time (regarding the total daily upload mass)

but this happens very rarely. please report us about bad ones and we will refund balance and try our best to replace such tracks with proper ones.
enjoy us
P.S.
ipodfan, when you see 160 or 170 kbps for VBR file, this is only average bitrate. it does not really mean that all the sound is low as 170 kbps during the whole playback. VBR will definitely drop bitrate when there's silence in the music but will increase it up to 256 kbps when rendering full orchestra and high noise percussions.
but your Winamp (or the like) will show you 170 average kbps in result.
regards,
skyforger