Any idea how to bias a push pull 50wpc integrated valve amp. The bloke that had this before me has swapped the tubes from stock 6550's to Russian Genalex Golden Lion KT88's, but I suspect he's not re-biased it. There's a hole for a voltmeter - I think* - and a screw next to each valve. I have a volt meter, what do I set on the voltmeter (as it looks hard) what thing do I poke down there, and what reading should I be looking for on each valve. Presumably switched on with no music going through. Hopefully the valves will be glowing blue and not me, I'm not very electrical! Its a Chi-Fi jobby so there's no manual! (*Chris's legendary electrical prowess coming to the fore.)