I've been using the Escient Fireball-120 system together with a Sony 400 disc carousel. It's a stand alone hard drive with 120 Gigs. You can use three daisy changed carousels slaved to the main unit, burn directly to the HD itself or a combination of both. Connected to the internet you can immediatey access CD titles, song titles and cover art which catalogues into the hard drive. It's a very cool system and sorts by music classification, WAV vs. CD etc. Too many amazing options to mention. CD burner built in. Plays continuously with random play options of all sorts. They've just upgraded the software so that you can communicate to your computer for backup purposes and even further cataloging options.
In terms of the sound quality, I have to say its amazing. Of course, I treat it like other sources in my system with vibration platforms, upgraded power cords, condtioners and occasionally an independent DAC.
As one who has tried all sorts of cataloguing methods over the years, this setup is a dream come true! Check it out.
http://www.escient.com/