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.