A y cable alone will halve the impedance on your pickups, which is tone suck. Better getting a buffered split to keep tone, and an isolated buffered split to lose ground loop noise that comes with split rigs. The Sansamp will do the buffering. Plus, if you want same thing going to each amp Might as well plug into one and slave the other one from it, if they have the appropriate connectors.
I use two different rigs, and have my bass wired with its own output for each pickup, much more tonal variety that way.
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