I have completed the wiring on the BeePre 2 preamp except for the selector switch and connections to the RCA inputs. Running voltage tests, I'm showing 6.36 DCV at both tube sockets, but when I insert the 300B tubes, the filaments light up but after about a minute they both go dark. Is something in the circuit causing a voltage drop? Whatever it is, any ideas about how to track it down/fix it? Thanks.
