Looking carefully at the specifications for the Quad 2805 (8 ohm nominal impedance, 86 dB sensitivity, and 55V RMS max allowable input voltage - - slightly less than 200W per channel) it would appear that either our Insight 440 or Fet Valve Ultra 350 amplifiers would be outstanding choices to compliment the performance of these excellent speakers. You would not need the "H" version of the Insight amplifier as the 2805 would be an easy load for it.
Note that at a recent AudioKarma show in Detroit, we lent an Ultra amplifier to an adjoining room where the owner was downcast because his highly regarded and very expensive loaner amplifier had failed trying to drive his pet speakers, two sets of completely restored KLH 9 full range electrostats, two speakers connected in parallel on each channel, talk about a very nasty load. The Ultra performed flawlessly for the show and the owner of the speakers told us he had never heard them sound that good before.
The prices are pretty close ($1699 for the solid state Insight, $1949 for the hybrid Ultra). I think your choice of preamplifier would enter into the decision. If you are using a soft sounding vacuum tube preamp, I would go for the Insight amplifier, with a more aggressive preamp, choose the Ultra. If money is no object, then I would lean towards the Ultra. Both amplifier drive full range electrostatic speakers easily and with outstanding musicality full range.
Thanks for your interest.
Frank Van Alstine
