Hi ghulamr,
You already have a very good system with high quality speakers that can reproduce very deep bass well. Can you tell me exactly what qualities you'd like to improve on the bass of your system?
I just read a very good review on your Von Shwiekert VR4 MKII speakers on Dagogo.com. In the review, he mentions bi-amping them using a pair of class D 200 watt Channel Island D-200 mono blocks on the bass modules with very good results. The D-200 monos are no longer made but there are many very good high powered class D amps that could be used instead. Class D amps are often used to drive subs because they're small, powerful,have low very low levels of distortion, have very high damping factors and are relatively less expensive.
Would you prefer to try this out before sub woofers?
Here's a link to the Dagogo review:
www.dagogo.com/channel-island-audio-plc-1-d-200-class-d-monoblock-amplifiers-and-xdc-2-ac-enhancing-... If not, I think you have 2 options for setting up a distributed bass array system in your room:
Opt#1- Custom DBA: Use your existing pair of VR4 bass modules as sub#1 and sub#2 of the 4 subs required. This option has 2 variations since you would need to buy either
A. 2 passive subs of your choice as sub#3 and #4 and the Dayton SA-1000 class AB 1KW amp used by the Swarm ($419 at Parts Express) or a class D 4 ch amp to drive all 4.
Or,
B. 2 amplified subs of your choice as sub#3 and #4 and either keep your current setup of not bi-amping your VR4s or biamp them if you'd like.
Opt#2- AK Swarm or Debra DBA: Keep your existing system as is and just buy and add the Swarm or Debra complete system with 4 subs and the class AB amp to drive them.
No matter which option you choose, I can help you with the proper setup procedure and any additional subs or amps you'd need. Opt#2, since it would actually consist of 6 subs in your room- the 4 Swarm subs plus the 2 VR4 bass modules) would likely provide the best quality bass and most bass (but controllable with the overall system volume control on the Swarm amp).
Please let me know your thoughts on this and removing the AV7005 from your system.
Tim