the 99 pre does not have the level of resolution the 909 has! For example: you could not tell the difference between the mediocre CDplayer and the better one listening through the 99. I replaced it with passive pre. the 909 has high gain (around 36 dB) and 20K input impedance so it could be matched with passive.of course you are loosing the comfort you would have with the 99!
Anyway my opinion (after 30years with Quad electronics and speakers)is that in every Quad generation the amps are better then preamps!