147 hum, XB-2 1147 pre-amp.

[I.Jackson@lancaster.ac.uk (Ian Jackson)]

I connect my XB-2 to a Leslie 147 via a line-out to a Leslie connector box
(one 5pin, one 6pin socket, side-by side, + sockets for Leslie chorale/trem
switch and reverb channel). I don't use a pre-amp.

With the 147 impedence selector switch in the 'open' or '16ohm' position, I
get loud hum from the Leslie that can only be cured by lifting the ground
on the XB-2 (the 147 is already ungrounded...).

With the impedence switch in the central '8ohm' position, there is no hum,
but then the Leslie volume is really low.

The obvious answer is probably to get a pre-amp, but:

Is the 1147 pre-amp kit available in a UK configuration (i.e. 240V mains
supply), or can the 110V version be adapted?

Why does the 16ohm or 'open' setting on the 147 amp give loud hum? There is
obviously a grounding problem, but why should this occur with the switch
set to '16ohms' or 'open', and NOT when set to '8ohms'?

Is there a workaround, to give the high Leslie output level of 16ohm or
open setting, but with no hum?

Any other suggestions for 240V-compatible pre-amps/configurations?

Thanks in advance

Ian Jackson