I have just purchased a pair of Quad 2805's and an REL B2 sub-bass. I have not had any problems with integration, or smearing. Bass imaging is presise. The REL is seamless with the Quad's as long as they are set up properly in the room. The REL is set to roll off at 36 Hz and with the fine adjustment it just disappers. The Quads also sound better in the lower mids with the REL connected.
I have not heard the 2905's but I have a friend who has and says the 2805's and REL sound better in the low bass than the 2905's.
I have not heard the 2905's but I have a friend who has and says the 2805's and REL sound better in the low bass than the 2905's.