Now the electrical side is all good, next came some physical issues. Then still the rotary encoders are a bit to eratic for my liking, the footprint of the little beeper is too large and the SPI bus is having some issues, yet I got it all to work! :) I also swapped the green LEDs I initially installed for some red ones I had lying around since the green ones were so bright they were hurting my eyes. I used the wrong footprint and had to bend some wired to make it work. Except for the bi-color LED that indicates MIDI activity. Swapping the NPN transistors for PNP transistors also got that problem fixed. Long story short the LEDs where on when they should be off and vice versa. I'm not sure what I was thinking while working on the schematic, but I messed up. Oops! Nothing that a few bodge wires won't fix however. For starters I completely forgot the connections for the power and panic buttons and the connection from the Teensy to the mosfet that powers on the device. I did however make quite a number of mistakes while designing the board. It's the first time I'm trying to make one. What I'm most excited about is the front panel.
All the potentiometers and buttons are gone in favor of two rotary encoders and the Eurorack inputs have moved onto small plugin boards. Finally the PCBs of the 2nd prototype arrived! As you can see it's quite a big change compared to the first prototype.