You can also leave out C13, C14, C18, Q6, R5, R31 R35 and R37 since those parts are only used for buffered bypass.
C8, R11 & R12 set the low-pass cutoff freq. The TONE control sets how much cut you get. It's called a shelving tone control because the amount of cut is limited by R14 & the TONE pot. The HP/LP switch also affect the overall volume, but that's just a by-product.This is the buffer section
I wouldn’t leave the hp/lp (high peak & low peak) out of the circuit if I were you... a lot of people thinks that stands for high pass and low pass but it’s not a filter switch...
As an alternative, isn’t the Blue Waffle basically the ADHD without the buffer?
Oh nice! I compared both and parts and the schematics do appear to be pretty similar. However, I'm not sure how the Blue Waffle will run on bass (which is what I play) but I'm familiar with how the ADHD/OCD will run on bass. I'm thinking the Blue Waffle is definitely one to try down the road.