Multiple Soundcards Under Linux?

Magnus Huckvale asks: "We'd like to kit our new flat out with a MP3/Linux stereo system, with a set of stereo speakers in each room. Does anyone have any experience with fitting more than one soundcard to a Linux box? Is it possible to synchronise MP3 players outputting to different cards? What other capabilities can we build in given the hardware? What (cheap) soundcard would do? PCI or ISA?" While this is an interesting question, I think it would be easier to wire both sets of speakers to one soundcard rather than fiddling with two (and the headache involved in getting both to work properly). What do you all think?