In that case, I will probably get a MP3 player and that card in next couple of months. I think eventually I've got my eyes set on the new Alpine Double Din touch screen unit coming out. But that will be a ways a way, if my wallet has anything to say about it. I read somewhere that the additional connector might be C-bus / Can-bus, but I can't find that webpage again. I hope that both the legacy and WRX could benefit from the same parts.
I'm not thrilled about soldering the traces, but I think I can pull it off if I'm really careful. I've done it before to fix some broken traces in an amp that was abused more often than used. Are you sure that the volume control is in the power amplification stage? I was hoping that the pre mps provided all the tone controls and volume, allowing me to tap and buffer those signals. I'm not going to do that if I have to run a separate volume knob.
Cool, I'll finish up the tax return and get myself an MP3/OGG player then.
Have you thought about rigging up an 8 bit shift register and clock divider to buffer the higher speed signal and use all eight of your input channels to read that single channel?
Well, I'll let you wander into that territory by your self, as I've seen more than enough magic smoke escape out of 100A IGBT's in my life. those things don't just fizzle, or even pop, it's like shotgun.