^^^
It's not about 'ignoring the naysayers'... He/She has asked for 'our' advice so we're giving them what has been asked for and in 'our opinions'!
Please provide helpful advice, not just do this and dont do that and ignore everyone else...
Anyways. Having looked at your system to me, straight away, the main issue is the C/A amp.
C/A are renowned for sounding clinical and again, IN MY OPINION and owning many sets of B&W speakers, their matching isnt the best.
If you were to audtion a decent Arcam, NAD, Musical Fidelity or Roksan amp you'd find that the B&W speakers will come alive much better and have deeper and more controlled bass.
I agree with the fact that speakers will never offer the bass weight that subs can do but thats like saying that a Robin Reliant cant offer you the handling of an F1 car!!!
IMO i think it would be worth you taking a look at some different amps before you go down the sub route.
The Arcam A85 & FMJ A32 amps would be good to demo as would the NAD C352 and C355BEE amps.