Not one but two very highly-regarded luthiers, both of whom have done quite a bit of a lot of excellent work for me over the years, swear that single pickup instruments invariably sound hotter than their double pickup-counterparts. One is a leading authority on Juniors, which of course have single pickups.
Both maintain that the presence of another pickup and the attendant circuitry, even when ‘isolated’ by the selector switch, has a significant negative impact on the quality of the output. (My dad was an engineer and had no truck with this ‘hi-fi voodoo’ and I studied science at school and university, and nothing I learned there supported this view).
It is not possible to prove this suggestion with most Les Pauls or 335’s, but comparisons between Les Paul or early SG Juniors and Specials, and between ES-330 T’s and ES-330 TD’s do shed some light, and from my critical listening experience, I think I agree with them. Hence my liking for single-pickup Gibsons, especially 330T’s – the only instrument of which I have two.
I carefully restored the wiring loom of a friend’s beautiful and otherwise original ’54 Goldtop recently as a long-previous owner had replaced the tone capacitors. Before I installed the vintage White Tigers I had sourced at eye-watering cost, I hard-wired each of the two P-90 pickups in turn to the jack socket. Wow. Talk about supercharging.
I have since read that many players supercharge their guitars by hard wiring a single pickup to the output jack.
I guess that when voltages are very low and components perhaps variable, strange things can happen. But I never have much time for those ‘expert’ dealers who put down single-pickup guitars, especially my beloved ES330T’s!
This is further confirmed by comparing my recent single-pickup purchases – a ’61 Epiphone Casino 230T and a 2012 custom shop historic ’63 Firebird 1 reissues – with their double-pickup counterparts.