You won't need a mixer as the built in preamps will be just as good and far less of a hassle. Personally I would go with the Alesis as you get more channels of i/o for the money.
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Quote by BrianApocalypse
Good call

Man, you should be a mod, you know everything.

Edited with what I actually meant! The Alesis doesn't have pre-amps though does it?