A: This is a perfectly valid question that we hear all the time. The initial answer is, probably. Of course the card will have to have analog or digital outputs AND inputs, and your software of choice will have to be able to recognize your sound card. Assuming these points are true, then you can use it. However, there are some issues with this scenario that you might consider.
Your computer’s sound card may handle digital data just fine – but does it do as well with analog audio? The inside of your PC is like an RFI battlefield. The inadequately shielded A/D and D/A converter chips on your PCI audio card are subject to constant bombardment by Radio Frequency Interference (high frequency noise) generated by high-speed signal lines. This induces jitter into the A/D conversion process that gets recorded on to your hard disk. Of course, once recorded, “jittery” audio can’t be fixed (sorry, no fixing it in the mix). But it doesn’t stop there: PCI audio cards draw their power from the computer’s main power supply. Computer manufacturers use switching-type power supplies that also generate substantial noise (guess where it ends up?). Loss of detail, clarity, width and definition in your soundstage can all be attributed to poorly designed converter and power supply circuitry. All of this adds up to (potentially) pretty nasty sounding tracks.
So, in the end, going with a professional audio interface that was designed for quality results is going to yield better sounding recordings than your sound card. Only you can decide whether that quality, which is substantial, is worth your investment.