For high voltage side, each channel draws about 50 ma, so total circuit consumes about 100 ma. Any tranny with 0.150 A 150 V-180 V should be fine, the supply is regulate no need to worry much about voltage. For heater, you need 2.5 A for 6AS7 and 0.3A for 6DJ8 so 0-9 V 5A should do the trick. To...