The achilles heel of the Quad/Gradient subs is the gradient s.s. crossover and its wall wart power supply. Keep meaning to ask someone to do a valve one for me. IMO, subs are needed if you listen to Opera or large scale classical works, otherwise the depth is not there.
Does the intergration with the Gradient and Quads work wellI heard some rebuilt 63's and loved the midrange, but not sure if would work well with all the music I listen to Thank you Bruce