Question/Advice on Wiring Pre-Amp and two Amps

I have an Emotiva preamp and two power amps (an Adcom GFA 5500 200 w/p/c into 8 OHMs and a brand new Emotiva XPA2 GEN3 490 w/p/c into 4 OHMs)

Speakers are Polk SDA SRS (4ohm) powered by the Emotiva and a pair of Polk RT55i 8ohm bookshelf powered by the Adcom.

I also have a Polk 15" powered sub

The Emotiva preamp has two sets of outpouts - one with a sub output and a set of outputs that are crossed at 90 hz and a set of full outputs (without the sub out)

My question is - would it be best to connect the Adcom powering the RT55i's to the crossed output and the Emotiva powering the big SDA SRS's to the full outputs OR use RCA splitter/pigtails and connect both amps to the full outputs of the preamp?

Thanks in advance