For simple 2-channel recording and stereo playback (of however many software tracks mixed internally), it's hard to beat the Digidesign AudioMedia or (preferably) AudioMedia II. They are available reasonably inexpensively from time to time. They have a pair of analog line-level ins and outs on the card (no breakout box required) with decent quality converters, and the II also has S/PDIF digital audio I/O on RCAs. Also onboard is a DSP that can be used (in Deck II multitrack recording/mixing software for example) for realtime effects, or with the hard to find and somewhat unstable TurboSynth, as a real-time modular software synthesizer.
Another useful starter system would be the Pro Audio Spectrum 16. Available for either Nubus or LC PDS, it has an external, software-controlled input mixer for four inputs (mixed down to 2), a mic level preamp, and MIDI in and out. DriverGuru managed to get two of them working in one Mac. The analog I/O is not considered as great as the AMII.
If you want to go to 4 or 8 channels of I/O, you will be looking for something like the Digidesign 882 or 888 external I/O rack units, with the appropriate Nubus card and cable. IIRC, the rack units will work with either Nubus or PCI cards, and it's the cable that makes the difference.
It may be possible to run more than one AMII in the same system, but I have no idea if the software/drivers will cope.
Another device you might consider is the Digidesign SampleCell Nubus - a hardware sample player with 8 seperate outputs controlled from a Mac software front end. Again, everything is on the card so no breakout is required.
And if money is no object you can always keep an eye out for a Lexicon Nuverb
Another useful starter system would be the Pro Audio Spectrum 16. Available for either Nubus or LC PDS, it has an external, software-controlled input mixer for four inputs (mixed down to 2), a mic level preamp, and MIDI in and out. DriverGuru managed to get two of them working in one Mac. The analog I/O is not considered as great as the AMII.
If you want to go to 4 or 8 channels of I/O, you will be looking for something like the Digidesign 882 or 888 external I/O rack units, with the appropriate Nubus card and cable. IIRC, the rack units will work with either Nubus or PCI cards, and it's the cable that makes the difference.
It may be possible to run more than one AMII in the same system, but I have no idea if the software/drivers will cope.
Another device you might consider is the Digidesign SampleCell Nubus - a hardware sample player with 8 seperate outputs controlled from a Mac software front end. Again, everything is on the card so no breakout is required.
And if money is no object you can always keep an eye out for a Lexicon Nuverb