subwoofer to digital music and movies


I am a bit confused on how to best play music and watch movies with my new subwoofer. My recent purchase was an Earthquake Supernova MIV 15 inch sub. My 2 channel music listening is all digital via Benchmark DAC1 used as a preamp and for home theater using my Marantz AV7005 preamp. Question is: how do I best connect the subwoofer such that it is part of the 2 channel listening experience (Benchmark) and playing movies using my Marantz preamp? 

Simaudio w5 (2 channel amp)
Earthquake Cinova Grande (5 channel amp)
Von Schweikerts VR4 + center + surrounds 
Benchmark DAC1 
Earthquake Supernova MIV 15
Marantz AV7005
OPPO 105
128x128ghulamr
Thank you for the response. I appreciate it. 
Couple of point - first I've read when connecting .LFE from Marantz you are technical using the Marantz processor to adjust the X-over frequency and at that point the subwoofer internals are turned off. 
Secondly - the questions remains how do I best connect both the high level line (speaker connection) on the sub for my 2 channel listening and also the .LFE from Marantz for HT. Is that even possible with this sub? Or will I need to purchase a REL? 
First point: Depending on the functionality of your Marantz it most likely sums the LFE signal sent to the Earthquake. Even so, the lest demand you put on room its  correction the better. Getting the subwoofers crossover and gain as close as you can before running room correction will lesson the equalization applied by the Marantz as well as give yourself a baseline of where you like the subs performance against that of the room correction software. The same goes for your speakers. The more evenly spaced and distanced from the listening position the less correction is needed. 

Second point: I believe the Marantz has a single subwoofer or summed LFE output SW1 which usually cuts off at 80Hz. The SW1 output is most likely  summed. I purchased an RCA Y-block to connect both of the subs inputs and heard no difference.

This manual may not match your sub but you should get a general idea of connectivity. Good luck with it and have fun in the deep end.

http://earthquakeeurope.com/Products/Home-Audio/Subwoofers/MKVI-12PIANO/Pdf/EU/MKVI-12PIANO_manual_E...
Thanks for the reply and it makes sense. The sub I have does not have the DSP and is one level lower supernova MKIV - which happens to have the high level input along with the LFE and hence my question on using both.