Your signal chain would look like this:
---> MiniDSP1 --> subwoofer amp ---> subwoofer
S6 RCA splitter -->
---> MiniDSP2 --> 4-channel amp ---> front speakers
or you can just run one MiniDSP to the 4 channel amp, and have the subwoofer amp do the crossover/TA for the sub. Depending on your install you might get lucky and it might sound "ok". But you will be leaving a lot on the table in terms of opportunity.
Unfortunately, if you buy two miniDSPs for a standard 5-channel setup then you have 3 open channels staring you in the face, and you start thinking "midbass array with additional derived center channel" and things get kind of squirrely. Which is where I am now.
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