REL Vs SVS for 2 channel music listening

I added an REL S5 about a year ago to my Tidal Contriva Diacera SE speakers and that really improved the room bass but then I recently added an REL 212 SE ....and kept the S5 for the lt side of the room and now the whole presentation is magical.i will,at some point,replace the S5 with another 212SE but for now, all is great.one of the REL VPs came over to help with the room positioning which save me a great deal of trial and error.

I have an older REL R 305 and its a nice sub.  I auditioned new speakers recently and paired it with an SVS and it was no slouch 

Calloway... 
I have an S5 as well, and chose it over the 212 SE.
1. Recently I've been wondering how much I am missing with the S5 vs the 212 SE.
2. I'm thinking one of the upgrades this year is dual subs, similar to yours. 

Thank you in advance for any response... 

Calloway how do you you have your RELs connected through Neutrik? Which REL is connected to what speakers and where do you have them placed? 

I just received the Antimode 8033ii yesterday and hopefully be able to set up today or tomorrow sometime. Do you leave the antimode on all the time?