REL G2 or JL Audio F112 ..thoughts for 2 channel

The Velodyne has both a low and high pass filter that limits the low frequency going to the main speakers. They recommend this connection if the main speakers are somewhat deficient in the low mids. It requires a high level speaker connection to the subwoofer. Refer to the pdf manual for any misinformation I may have provided.

Using the Manual optimization software you can see your main speakers behavior below 200 Hz

Since you're so close to the Marchand I'd suggest trying the active crossover last.

REL has the advantage of being able to blend high and low level signals. OTOH, at least of the REL test report I read, the REL simply added a sharp bass spike centered around 45 Hz and it was entirely up to the user to move the sub around the room and fiddle with levels and placement to get this spike to broaden via room boundary reinforcement and blend with the rest of the system. Measurements here.

By comparison, the JL had a broad, flat frequency response that didn't start rolling off until around 20 Hz. The JL drivers are a thing to behold, with massive, deep castings and a magnet that could probably pull a car from across the street. If you're really down to JL and REL and you are willing to spend REL money, you *really* need to audition JL. Fathom F113 measurements here. JL subs are essentially flat from 20Hz to 80-100 Hz depending on model.

I also read a review of JL's entry-level F110, where the reviewer felt the 10" sub flap his pantsleg from 10 feet away. The F110 is about the same price as the REL R-328.

I heard JL F212s blended seamlessly with Magnepan 20.1's. If they're fast enough for panels, they're fast enough for anything. Also, they are capable of such high output they can be brought out into the room next to the stereo speakers.

Johnnyb53....thank you, this is exactly the inforamtion that I was looking for and some of it I did manage to find online. But you nailed it ...based on my room the JL Audio's F110 is the one that I think will be best of the two ( REL - JL ) and if I like one I will get another and add on a exterior crossover unit. Thanks for all of your help !

Garebear, "There are many who find REL to be…" I can see were that might be confusing. No, I'm not one of the many.

IMO most subs can be musical if they can be properly controlled and equalized within the environment to create a seamless integration with the main speakers.

I guess I am lucky, I don't know much of anything about integrating subs. Just read the instruction manual, stuck it in the corner and adjusted till it sounded "right" to me, and sounds just fine to me. Just one little REL T9 is all I needed for my big basement room. Maybe I am easy to please though so Good Luck with your sub choice.