In need of some advice on a matching a sub


Hi guys new to all this just wondering if anyone could help me out, im currently running a 5.1 (without sub) system im using kef reference model 4s for fronts model 1s for rears and a 200c center speaker im running all this off a avc a1-hd intergrated amp, ive done some reasearch and been told to pick a sub very wisely as it will make or break the system just wondering if you have any suggestions thanks
spankycrf
yeah I did think that I’ve currently got my rears and fronts set to large on the settings, the majority of my use is movies but I do on occasion listen to music and as I’m looking to spend a big chunk on a sub was wondering if there was anything out there that would do the best of both worlds, I contacted kef and asked about the 209 subwoofer but I just can’t warrant spending £6k on a subwoofer, I’ve also been advised against goofing for that sub as there is another one on the market and you can get 2 for the same price and with those two it produces a better end product than the single kef I never use to have this issue I used to use he model 4s for stereo using a nad 600w per channel power amp and a hitachi pre amp (both old I know my dads old stuff) I bi wired the two fronts and that made a big difference just not enough wondering if I hoocked the nad up to the dennonif that would make the fronts produce more bass then I could bi wire the rears instead 
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Hi 

I fell in love with JL Audio subs.  Had a 12 and switched to 2  10's  I found that all I need is one JL Audio E110 and it gives me all the thump I need.
So I am selling the extra E110  It is about 10 months old and would sell it for 1400 plus shipping if you are interested
 
OK if not interested but I highly recommend JL Audio

NormL