I have a very similar setup, with Aleph 3's and Quad ESL 63's. I tried it first with 8' Stealth Ultimate Ribbons and then with 18" lengths of the same cable. My experience: it is VERY MUCH WORTHWHILE to go for the shorter length! The 18" cables brought me MUCH closer to the music. I thought it was very good before, and maybe it was by any reasonable standard. But this was one more reminder of the audiophile mantra, "It can always get better."
Speaker cable length for mono blocks
I shall soon be attempting to either vertically biamp or mono amp a pair of speakers. I can put the amps within 6" (inches) of the speakers if I wish. Should I connect the amps to the speakers with very short lengths (less than 2 feet) of quality speaker cable (12 AWG or greater) or should I hook up a conventional length (eg. 8 feet) of cable? The amps will be Pass Alephs and the speakers will be electrostatics.