Afterlife Input Sensitivity Question

[Idgaaa]

Hi folks,

I'm planning on including an Afterlife Compressor in my Bass Guitar Tube Preamp and I'm wondering how the position of the compressor in the signal chain affect its sensitivity. With my limited knowledge on circuit design, I would assume that it wouldn't really be useable after a gain stage of 60. I know it says to increase R7 for higher sensitivity in the build document, so I probably should just reduce it to around 1k and work from there.

But nosy as I am, I'd like to understand and be able to give a rough estimate of the values before tweaking them.

So how do you calculate the gain for the Afterlife? Is it R3/R4+Sustain - diode clipping? And how does R7/IC1B fit it the mix?

Thanks for the help!

Schematic attached for ease of discussion.