Quad 2905 versus Quad 2805 plus subwoofer

I bought an Antimode 8033 cinema and it works a treat. Room modes have virtually disappeared. The sub now sounds as tight and fast as the main speakers. Bass extension also seems even lower. Even with boomy recordings the sound is much improved. There is only a little bit of experimenting left to do, and then I can stop thinking about audio, and just enjoy the music.
Willem

I have 988s fully upgraded by Electrostatic Solutions and with the Mye Stands. I recently bought an REL S5 subwoofer and find that the reviews were correct - it blends in seamlessly with my Quads. I have the REL engaged at around 35 CPS, so the REL supplements the full range Quads. Highly recommended.

I have my sub filter set at 33 Hz and a steep 4th order slope, so probably with a bit less overlap than you have.