I'm helping my church tweak and improve the sound, and since there was room for a small PC in the control booth, I got curious if WMP 9/10's SRS WOW and TruBass features can be used on live signals?

The goal is to get the music and vocals out of the mud and more distinctive, without blasting the paint off the walls.

Do the signals have to be encoded to digital files before it will perform the DSP effects? Or can it be applied to a live signal?

The keyboardist's sequencer is the main thing we're trying to improve on. It only has one set of audio outs, but no way to adjust volume on the individual instruments (strings, extra drums, horns, etc). If the output could be run through some type of DSP (like in WMP) to expand and add clarity, that alone would help things alot.

What other software-based DSP apps can do this?

You could use a computer as a really flexible effects unit, which some people do. You need a sound card that supports low latency drivers that work with the program you wish to use (i.e. Sonar). You can use plug-ins that your audio program supports (nearly all of them support directX stuff). I'm not sure which particular plug-ins will help you in your situation. If everything sounds 'muddy' as you say then it's probably a combination of bad room acoustics and bad equipment. It could also be bad mixing or bad mastering (in the case of certain rock/pop CDs, which are super super compressed).

If you go the sound card route, then there will be a delay of a few miliseconds as your sound card has to sample the audio, process it, and then spit it back out. In applications like having the band monitor the processed audio, the delay isn't good as they'll hear flanging. For the sequencer the delay should be ok. How long the delay is depends on how powerful the computer is... AMD processors are the best for this *particular* application (AMD64 ones being the best performing, and AMD XP mobiles being the best for low computer noise). The delay also depends on which plug-ins you use.

I have no experience with the above and that's what I figured out from what I've read.