Effects loop or line out for a Plexi?

[Madison]

My friend wants an output jack for his rack guitar tuner.
I'd give a simple line out just off the input jack but he specifically wants it to be non loading on the input signal. within the preamp section.

I found this mod.
http://ceriatone.com/images/mods/Plexi50-with-interrupt-styl.jpg
Is this the simplest way to go about this mod?

I though the effects loop might be a better option than just a "line out"?

[LooseChange]

Sure, that will work. Plus he could go through the tuner and back into the return and cut the signal when he tunes. My concern for these is the high gain that can be sent to the pedal.

I would not ground it on the speaker jack. Better place is the ground of the phase inverter and then you could run a shielded cable (Or all three twisted).

[Madison]

Yeah cool.I think........I am going to try this.

Forgot to mention.
It has a MV (more like the JCM800).
So, would I still go off the center lug of the Treble pot or the MV pot?
Which would work best?

I wonder if it would need yet another pot on the output to control the gain.
He was saying his tuner only needs a bit of signal to work.

>>I would not ground it on the speaker jack. Better place is the ground of the phase inverter
I too suspected there might be a better place for grounding.

>> run a shielded cable
Shielded cable galore.

Thanks Dan!