Hi Sabby,
My experience with LP12's is that the power supply influences the whole sound of the deck quite profoundly. Rythm, pitch and timing are a result of the platter turning at the corect speed, with as little motor vibration as possible, so this aspect affects the performance of any arm and cartridge that's fitted. As the Valhalla boards tend to be very old now and they often fail as a result, you can get a Hercules board for around £250 fitted. This replaces and fits in where the Valhalla goes, inside your LP12, gives 33 and 45rpm and much better musical performance. The Naim Armageddon type uses a large torroidal stepdown transformer with capacitor supply - better sound, but only 33rpm. To play 45rpm with this supply you need a 45rpm adaptor pulley that fits over the 33 pulley. The Linngo, however, gives the very best improvement with second hand ones going for £500ish, this is a much more sophisticated supply than Valhalla or Hercules.