hi, not really chopping it up, i just want to try a vintage blueline preamp through crown modern amps. on the schematic, (thanks dr tube !) pins 1&4 are the output, it looks like i only need 6.3v to the power the filimants on 7&8 , but on pin #5 i cannot tell what it needs. my only guess it is plate voltage, i could measure with a multimeter, but i dont know if its ac or dc. am i missing anything else to make this work ? thanks, johnny a.