SPEAKERS, SPEAKERS AND MORE SPEAKERS.. BUT NEED BASS.?

Sub Woofer option works well. I got 2x JL audio Subs connected to Avantgarde Acoustic Duos. The Original Subs are disconnected. Running with Ayon Mercury Tube AMP and Ayon Stealth DAC... Astonishing sound and Bass.....

Listen to Niki Minaj - Queen album if you like bass.

Another suggestion would be the new Usher mini dancer ii’s with the DMD tweeter. I just sold a pair for < $4000. The Usher DMD tweeter has 1 of the best tweeters on the market. The MD ii’s have very good bass too, read all of the reviews. I moved up the Usher chain to the X-Towers. 

SVS subs are terrific, but you won't need one with KEF R 700's (currently available at close-out prices). You will need quality, high current amplification to drive them.

Shameless post by questforsound. 

Spend a a few dollars and buy an ad or send the OP a PM. 

Having been around the high-end audio for 20 plus years I had a great experience with a pair of Monitor Audio PM 702 gold on a 26 inch stand running a Parasound 2200 sub (then upgraded to a REL 328), great imaging & detail. Cost less than 2000-. MA very efficient, but still need good electronics.
My room: 15'w by 18' deep L shaped room w lots of carpet & 8' ceilings & well insulated.
I ran this w what I would consider neutral to warm electronics (Bedini & direct to Oppo) , but I would be concerned about recommending that combination with your electronics.