Know it's almost 2 years since your original post, but have schematic if you still need. Have had my Laurel 300B > 20 years now, still listen to daily. Replaced output caps with Mundorf and some other caps with v-caps. Mundorf was big upgrade. Have rolled several pairs 300b, currently using Takatsuki, but have tried Sophia Mesh Plates, Vaic Valve Blue Glass 300b and Sovteks. Bought the Takatsuki at an amazing store in Tokyo that sells only tubes, have never seen anything like that. Honestly, I'm totally happy with this - amp plan on keeping forever. Have also rolled the input tubes, makes less difference than the 300b. Using RCA now. Finally, the rectifier tube matters - ran through a couple, finally got a Mullard. Am surprised rectifier makes difference, but it does.