Hooking up my JL sub

Probably the easiest and best way would be to use either an electronic crossover, or just simply use a y adapter.

Benchmark DAC 1 has both unbalanced and balanced outputs, the unbalanced rca output connect to Marantz AV7005, balanced xlr output connect to JL F112 sub xlr input directly or via a switcher, so no 'y' cable/adapter needed.

Yes, if it has both outputs that is even better.

ozzy

@imhififan 
Benchmark DAC 1 has both unbalanced and balanced outputs, the unbalanced rca output connect to Marantz AV7005, balanced xlr output connect to JL F112 sub xlr input directly or via a switcher, so no 'y' cable/adapter needed.
That will not work - if Marantz is the preamp the signal will generate from Marantz to the sub. 

Passing signal to my Marantz in Pure Direct mode cuts the signal to the subwoofer. Can I use a RCA Y splitter and pass one signal to Marantz and the other to JL audio?

Maybe I misunderstand what you want to accomplish, since the DAC1 has both unbalanced and balanced outputs, and your Marantz AV7005 only accept unbalanced RCA analog input, I assumed you connect the DAC1 to the AV7005 via unbalanced cable.
You can connect the DAC1 to the JL Audio F112 sub via balanced XLR cable without using a Y splitter or LOC!. To watch movies of course you need to swap input of the F112 by plug and unplug both XRL cables from the DAC1 to AV7005 LFE output or using a A/B switcher.

https://www.amazon.com/Audibox-Switcher-Stereo-Signal-Switcher/dp/B00ASVXBO8