Frank, you are welcome.
The Bypass switch makes a direct connection from the phono stage output to the line stage input. It bypasses the Source, Monitor and Mode switches, plus the Line Stage Gain switch and the Balance potentiometer. It was clearly designed to optimize LP playback sound quality. I have attached the schematics URL.
Scroll down and click on the schemos to enlarge.
You may also want to replace two 6L6GC and one 12AT7 on the HV regulated power supply.
I forgot to mention in my previous post: photo-transistors degrade sound quality (IMO, loss of "air" and high-frequency detail), so I recommend a hard-wired Mute switch across the preamp output. The switch, if wired as suggested, is entirely out of the circuit when un-muted.
Have fun!
Edits: 06/11/12
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