Speak to Audiogon member Dlanselm...He owns these speakers and has done much comparison auditioning!
I had a pair of 2805's and found they did not like my tube preamp and SS poweramps. I eventually used a passive preamp and a pair of Quicksilver V4 tube amps that played very nicely.
The guy that purchased my Quads came over to listen and we connected his Musical Fidelity A3 CR, this was also a great match, with deeper bass than the V4's.
The speakers also did not play well where I had all my other past speakers placed. They sounded best in my room on the long wall where I then sat ~7 feet from the fronts.
I found that tube amps seemed to work the best with my Quad 2805's.
McIntosh 275 MkV - this was a very good match. Very dynamic with good bass, midrange and treble. I liked this combination the best.
Rogue Cronus - Used EL34 & KT77 tubes. While I loved the midrange presence, ultimately I decided more power was needed and I wanted more bass and treble than these tubes provided.
Manley Stingray - I love the EL84 tube, but even in my relatively small room this amp did not have enough current to adequately drive the Quads.
Like Wings mentions above, I prefered to listen to these speakers closer that other speakers I have ownen typically listening about 7' - 8' from the fronts of Quads.