From about December 2010 onwards we started making our preview audio in 128-kbps MP3 files (higher fidelity, more clarity) and also with a "preview.... shockwave-sound..." voice that was both mixed at a lower volume generally, and that also changes in volume dynamically depending on how loud the music is at the moment. So if there is a really quiet part in the music, the preview voice is also at a low volume. And vice versa.
This did however leave our older tracks sounding a bit "second grade". There were some 5,500 tracks, all with multiple versions / edits / mixes, and a total of 38,770 "old" preview files on our server, and with a bit-rate of only 56 kbps and with a preview voice that was, at times, way too loud, these tracks just didn't sound as attractive as our newer tracks.
Anyway - we have now just finished the rather large task of updating all those 38,770 older preview files to the "new" format. We had some good people working on automating this task, so it wasn't as bad as we had feared. It took us a few days of audio file processing, plus about 10 hours of solid uploading. Now all our tracks - old and new - have preview files with a nice clarity of sound, and a preview voice that shouldn't be too obtrusive.
Just one of the several upgrades and improvements we are working on here at Shockwave-Sound.com this spring/summer.