Guitar step sequencer

My first post here. I’m relatively new to the Arduino environment but yesterday I made my first project where from start to finish I did everything myself. It’s a simple guitar “effect”. Instead of describing what it does, here is a video. I didn’t technically use an arduino as you can see, but it’s written in arduino code.

All I’m doing is writing HIGH to the base of 2N2222 transistor (which grounds the hot wire of the audio cable) and then LOW with a delay between them and a pot to control the delay.
While that’s cool and all I thought the next step would be a step sequencer where I control the volume of each step (with pots). What I need help with is… How can I control the volume? I looked at digital potentiometers with SPI interfaces but potentiometers in passive guitars are normally 250-500k and I couldn’t find any digital pots like that. Any suggestions?
Also, is it bad to ground the teensy and guitar/amp together?

Thanks :slight_smile:

Volume control - how about running your guitar into an op-amp, and use digital potst to control the gain of the op-amp? Then the smaller value digital pots would be fine. I would think you'd want the guitar & amp & digital pots all grounded to prevent noise & hum issues.