The big question is, do you have a mixer capable of sending 8 seperate signals into the soundcard, or do you need an all in one solution?, both have their pros/cons, but in my opinion using a "real" mixer is really the only way to go, you could get by without one, and something like the Aardvark Q10 would get you started.
I find the routing/monitoring and effects monitoring on an actual mixer combined with a nice headphone amp and an outboard reverb/effects unit to be indepensable.
I use a Delta 1010 with a Mackie 1642 and an OZ audio 6 channel headphone amp.