What sub for my Naim AV system?

I have a Naim system made up of 102/2xHI-CAPs/SNAXO2-4/4x135s/ALLAES

Integrated to it is an AV2/NAP175/n-SATs/Linn EKWAL centre

It sounds very good, but I would like to use a sub to get some proper low frequencies. Currently if I set the front speakers to large on the AV2 I get low frequency cracking occasionally, setting them to small will fix that, but then low frequencies go missing.

I would love  an n-Sub, but they seem to be as rare as rocking horse do-dos.

Moderated Post:  Tiggers55, please ensure you have read and understood forum rules.  Thanks.

Original Post

+1 for the REL - I have a T9i in 20-25m2 area. Hooked up with high-level input from the (non-Naim) amp speaker terminals. Good review by Alan Sircom Hifi+ about how the RELs are integrated into a system for musical bass enhancement rather than 'in your face' subwoofery. 

ChrisSU posted:

I was lucky to pick up an N-Sub a couple of years ago, but if I didnโ€™t have it, BK would certainly on my shortlist. 

I was even luckier to pick one up in Maple, the same veneer as my SL2s, Axess & n-Sats. Took months of scanning the classifieds but well worth the effort. 

BTW, why are all bar the top 8 threads on here now closed to replies? Are Naim thinking of shutting down this section of the forum?