Unofficial winamp plugin for Liquid Audio: http://members.tripod.com/~vfnac/
Liquid Audio FAQ: http://homes.arealcity.com/absafaqn/
I read somewhere that Liquid Audio is working on an official winamp plugin. The unofficial winamp plugin works but it does cause winamp to crash more than just occasionally. Also, there is no support with the plugin for tag info so the only display I got on my 4 x 40 parallel LCD was the filename scrolling. BUT... the sound WAS... well, you'll just have to try it and see.
It's my understanding that Liquid Audio is a commercial implementation of the Advanced Audio Coding standard. There IS a "freeware/non-commercial use" AAC encoder with support for id3 tags: http://www.slimline.net/aac/
Look for an AAC winamp plugin there too.
Encoding and decoding both take more processor power than for mp3 but I find the results worthwhile.
The first night I tested the "Liquidcar" it was raining pretty heavily. I had ran across the plugin/encoder earlier that night (just before bed) and thought that I would test it the next day. I soon realized that I WOULD NOT SLEEP until after I knew what it sounded like in the car (can anybody relate to this? ha!) Well... I just had to go for a late night drive in the rain.
Wow! Big difference in imaging!
Wow! More musical!
OOPS! Frequent rebooting!
One of the albums I listened to was "Strata" - Robert Rich/Steve Roach. During a particularly wet part of the storm [that I was driving through] the track "Grotto of Lost Time" came on --it has a background of very realistic sounding dripping noises...
I get pretty good results using the freeware AAC encoder/winamp plugin. Recommended for FANATICS ONLY though cause it takes more processor both for encoding and for decoding. As an example: a recent CD encoding session on my P90 took 24 hours. This was for ONE CD.