Hum with a Decca... help!

Hi All,

I wasnt sure whether this should be posted here or not as I dont think its a problem with the valve gear, not sure...

I recently re-assembled my hifi after a couple of months of prolonged house move and room redecoration. However Ive been busy! I have sold my Goldring, had the Decca London retipped along with replacing the original Decca plastic mounting caddy with the metal variant, bought a new arm (Hadcock), replaced the solid state pre with a passive from Creek. So the system now is an LP12, Hadcock, Decca, WAD Phono II, Creek passive pre, 300b PP poweramp.

I set everything up last night. Excited as I had been without a music system for about 9 months. But oh dear problems.....hum. Quite a lot and also quite loud. After much cable moving rearranging plugging etc I couldnt remove it. At a realistic listening level its quite apparent, so the hifi is currently unuseable
I dont think the problem is amp or cable related but I could be wrong. If I short the cartridge pins out even with the volume turned to max there is only a slight hiss. I think it may be the cartridge. I seem to remember reading somewhere either in a magazine or on the web, that Deccas can produce hum under certain circumstances. 5 years ago with all my solid state gear all seemed to be ok.
Has anybody any ideas or experience with anything similar. I really would like to keep the Decca (because its a great cartridge!) but if it siimply isnt compatible then Ill have to move. But is it the cartridge and is there anything I can do to alleviate the hum or tests to prove one way or another?
Thanks for any help,
Matthew