Amp FX Loop

[sonolink]

I built an 18w tube amp for a friend some time ago. Now he would like me to implement an FX loop to be able to use the power stage with other preamps.
I have attached the original schem with the mod drawn in red (between the pots and C9). Would that work?
Thanks for your time and help
Sono

https://ibb.co/44SHv0t

 

[Bo Deadly]

What was the 470K in the PI inverter attached to exactly? Maybe you should post the original unmodified schem.

Note that tapping into the vol control will make the send output impedance quite high potentially. And the level will be too high for pedals.

But if you're just using the return, it might work ok.

 

[sonolink]

What was the 470K in the PI inverter attached to exactly? Maybe you should post the original unmodified schem.

You're right, my bad
Here is the original schem:

https://ibb.co/y4MmRqC
And here is the modded circuit corrected:
https://ibb.co/XLvM7LZ