I have the m10000 motherboard. I used onboard sound and it sounds bad. Not terrible but bad. Give me a headache. The audio was also very low and I had turn everything up really high.
now I'm using Turtle Beach Audio Advantage Micro. The sound is a lot louder but the treble seems very loud.
The front end I'm using is Roadrunner with winamp installed.
The biggest problem I have is when the music is low, I can barely hear the lyrics, all I hear is the music and bass (annoying when listening to hip hop because too much bass and can't hear lyrics cleanly). When I turn it up high (to hear the lyrics), the treble and volume makes my ears hurt when I listen to pop music.
I tried playing with bass and treble on my car setting and it helps but not too much. I mean the radio and cd player works nicely but the carpc doesnt.
Sorry if I'm not clear.... I'm going nuts with this after spending so much money on the project...
For the M10K onboard audio, you likely had old drivers. The drivers it ships with are crap and sound like it. You need to get updated drivers from via arena. As to your other sound card problems, I am no help there.
First make sure all drivers are updated. I use a VIA PD mobo (similiar) w/ onboard sound and it sounds great. Might want to start from the beginning... make sure all cables are secure and pushed in all the way, turn off any EQ on your HU (or to a flat setting). On you computer just open up winamp (not Road runner) and play some songs and see how they sound. Will also want to check out the windows volume control panel and make sure your volume faders are turned up. Also go into your windows sound/audio properties and make sure you have the "speakers profile" set to normal stereo desktop speakers and not something like headphones or laptop speakers.
So make sure all the windows audio/speaker settings are ok and then play around with the Winamp's EQ settings.