Needing help with a physical MIDI sequencer project...

Hey there,

i really need help with a project I am doing for University. Basically, I am rebuilding "GRIDI" ( please watch the video on www.gridi.info for more information, explaining is always a little bit difficult...), a large physical sequencer that works with balls that are placed in the music grid, in smaller dimensions.

My Code isn't finished yet, but it is able to turn on and off the LEDs at the right moment and detect pressed switches if a ball is placed inside a hole.
Problem is, I didn't really think about how I produce the sounds until now and thought it would work with a Music Shield on the Arduino. Yesterday, I had to see that the shield I ordered (Seeed Music Shield V2.0) isn't able to play two sounds at the same time and apparently also no other music shield out there is able to do this, too.
You see, I need another solution for producing the sounds. The original GRIDI is connected to a synthesizer software (Ableton Live) somehow...
As I am a bloody beginner in this field, I would be very happy to get some understandable (not filled with shortages and mysterious letter combinations) advice how I could do this - I already found out that "zynaddsubfx" could help me, as it is maybe able to connect with the Arduino - but I still have absolutely now idea of how to do this and could not find any helpful advice until now... The software should be able to place a note in the synthesizer grid every time a switch on the physical grid is pressed.

Just some more details (as my code isn't finished yet, I will insert it later on): I am using an Arduino Mega and building the "grid" out of 8 rows and 5 columns (this is, 8 beats per sequence and 5 possible instruments or sounds). Thus, I use 40 switches that I connect to 40 pins on my arduino. Another pin is used for the LEDs. I am using 40 Neopixels (a programmable strip of LEDs) that are connected to one pin. I will build in a potentiometer to control the speed of the beat going through the grid.

If you need more details, just ask!
I am looking forward to some helpful advice - thanks in advance for these!

Why not have your Mega send MIDI to Ableton and have it generate the notes.

Take a look at my tutorial on how to build a MIDI controller using an Arduino. The principle is the same for a sequencer, but you only need note on and note off events (and no control change events).
(You're probably most interested in step 9, that's where I show an example for using switches. You can easily adapt the code to work with your sequencer.)

The advantage is that you can do everything over USB, no need for extra MIDI to USB adapters and things like that, just plug and play!