Small footprint subwoofer

I have a REL S/510 which I like a lot. I don’t like looking at subs so I wanted the small form factor 

Thanks for the response. The room null I am have right now is above the xo point anywhere around 90 to 120hz. Most likely is due the position of the speakers and the in room response. The node is at around 60hz so I have corrected most of the issue with a inline 12db/slope 70hz crossover for the speakers and the sub setting at around 50hz. Theoretically this would be a 6 db less at the xo point. On the contrary, the null that I have is probably more complex to fix. Honestly, this is a bad room dimension but it is the only room in the house I can relax.

As far as the position of the Hsu sub, yes it is in a near null position by not quite. That is why it is off centered to compensate the difference. I have the tools to do measurements so finding the best place for the sub is not a problem.

I decided to go with the REL R218. This came with the high level cable. I have the option to high level or line level signal. What would be better to use on? For the high level, I am using an Adcom GFA-5500.

I like using the REL cable.   They recommend it and it works with most amps. If your Amp is fully balanced at the output , which i think it is , then I believe you do not want to connect the Black ground wire.  Only the Red and Yellow.  Float the ground Check with REL before going speaker level. 

I respectfully disagree you don’t need a sub that goes below 30Hz for music even in a smaller room. There’s actually a lot of

+100