Subwoofer cable output to banana plugs

Originally Posted by A9X-308 

Looks like line level pre out on the back of the AVR and a speaker banana plug connection on the wall. They are not compatible.

You'll need an amplifier to power the sub, connected to the AVR sub outs as well as the banana plugs to the wall.

Originally Posted by maxcooper 

You need an amplifier.

Tell us what you know about the subs and we can help you find a suitable amp. Model numbers, pictures, etc. are all useful information.

Here are some amps. Review these, and that will help you identify what is important to you / what your constraints are for the amp.

Behringer iNuke 3000: Lots of power for the money. Has a loud fan in stock form, but you can swap in a quieter computer fan. Very lightweight. You will need some inexpensive but uncommon plugs to connect it: RCA-to-XLR for the inputs, and Speakon outputs. Ugly -- silver with a bunch of orange lights. DIY audio people think this is "small and inexpensive", but I suspect that non-enthusiasts would see it as "large and expensive". It's ~$300.
http://www.amazon.com/Behringer-NU3000-Ultra-Lightweight-High-Density-3000-Watt/dp/B005DUR7U8/

Crown XLS-1000: Quiet, even though it has a fan. Has the common RCA inputs and binding post outputs. Less power for the money than Behringer, but also more convenient for home users, and Crown has a better reputation as a brand. There are more expensive models with more power if you need it. Still ugly in a home setting, but less ugly than the iNuke. Also light, small, and relatively cheap by DIY audio nut standards, but large and expensive by non-enthusiast standards.
http://www.amazon.com/Crown-XLS1000-Amplifier-integrated-Crossover/dp/B003HZPKSM

(There are similar models for the amps above with more power, if needed.)

Behringer EP4000: This is a really popular sub amp. Lots of power for the money. Big, heavy, and has a loud fan. Was on sale recently for $275, but still a reasonable deal at the current price, though I would get one of the amps above instead since they are easier to work with (weight, fan noise).
http://www.amazon.com/Behringer-EP4000-Professional-Accelerated-Technology/dp/B001U5JFNM/

Behringer A500: Less power than the first two. Silent, since it has no fan. Heaver than the first two, but still not that heavy. Has common RCA inputs and binding post outputs.
http://www.parts-express.com/pe/showdetl.cfm?partnumber=248-749

Dayton DTA-100a: This is not normally used as a sub amp (it isn't "popular" like the ones above), but it could work as one, and it is small, silent, and relatively cheap. I'm not sure it has enough power for your application, but it may be worth consideration.
http://www.parts-express.com/pe/showdetl.cfm?partnumber=300-383

-Max
(I own all of these amps, or a variation: iNuke 3000DSP bi-amp center, Crown XLS-1500 sub, EP4000 unused, A500 garage sub, DTA-100 bedroom system)

Originally Posted by Martycool007 

Wow, that is the oddest place I have ever seen anyone put a subwoofer. To answer your questions, I am sure that you could do a whole hell of a lot better going with regular speakers and a traditional subwoofer or two. Your in-wall speakers and subs are not going to provide very good sound quality, as very few in-walls that I have heard do actually provide a good theater experience. If you are handy using a saw then I would strongly consider doing a Seos build as you can get those for around $250 to $450 per speaker depending on how high up the chain you want to go. You can actually purchase the Seos flatpacks that come with everything you need to put them together, ie drivers, crossovers, ect...plus they come with all of the wood pre-cut so all you have to do is assemble them, no need for any sawing or the like...For your subwoofer, I recommend purchasing a flat pack for that as well, and going with the Dayton HO15 or HO18 with possibly a Behringer EP4000 amp.

Ok, sorry, I am getting a little bit ahead of myself! Your sub will need an amp, but I will be honest, you are kind of throwing money in the wind with that thing. You need a traditional subwoofer, preferably two or more. The receiver has built in amplifiers for the speakers, ie Left, Right, Center, Surrounds, but the subwoofer output on your receiver does not have a built in amplifier, you will definitely need to either find a sub from the likes of HSU or SVS, or Epic, as all of those have built in amps, or you could build your own. I recommend the later as it will cost less if you build your own, plus you will get much better bass for your dollar by going that way.

Originally Posted by Bill Fitzmaurice 

+1. That system is perfect for a hotel lobby or restaurant. For a real HT, not so much.