On 08/03/2015 11:34, Sumatriptan wrote:

it's a pigs ear.


Just for closure on the hum issue...

I corrected the wiring errors causing the L-R reversal and phasing
error. I also fitted the Behringer phono--USB into the turntable as per
suggestions in this thread. The (good quality) screened cables from
tonearm wire connectors to the Behringer phono inputs are now about 3 cm
long. Hum is now completely gone. At maximum volume with tt motor
running the only sound is a small amount of noise, presumably from the
preamp front end.