Work for Sax and Black Midi

Hello! I composed a short thing for a theory final (post-tonal) and decided to hit two birds with one stone and write it as my upcoming piece for sax and recording. I am struggling to figure out what sounds I should go for in place of the lame piano midi I wrote this with. Can any of you give this a listen and give me some help on what direction you would orchestrate this with?

The other movements I plan to have be with recorded synthesizers, but the ones I have in GarageBand did not fit this movement here. Do you guys know any programs that let me export the quarter tone midis into it? Garageband reverts everything back to 12TET. The saxophone part is being written for my amazing friend, so I think it will be possible! However, this is more of a rough draft and I want to have more meaningful notes in the final.

Hope you enjoy! I think this is a cooler thing I have composed, even if the accompaniment is not really playable.

Audio: https://drive.google.com/file/d/1smGKW85ZJtaAn_hLW2yq-9L_72oTIqpv/view?usp=sharing

I'm no expert on microtonality, and some of the microtonal chords you use are quite thick, but couldn't this be played by a bigger string orchestra?  Like I mean, a string orchestra with more than just two Violin parts and etc.  Also, I think strings are adept enough to be able to play the microtonality, even if you need lots of them to fill out those chords you have, unless you find some clever microtonal double stops that aren't too difficult for the players.

Despite the microtonality, I like this music.  You seem to use it sparingly, as if modulating only sometimes to half-flat keys.  Also, I noticed that the saxophone part doesn't seem to have any microtonality in it.  I guess playing microtones with special fingerings would be more difficult.  Btw - are you using 24TET in this?  Since you don't have any special performance notes/special tuning indications, I assume it's 24TET.  Cool piece and thanks for sharing!

It's pretty solid and beautiful. Answering your question in the chat, I am not sure if you should change the piano, I like how it sounds honestly despite as you say it be not playable by a single pianist. If you did really need to replace it, I'd go with strings and brass too, why not, and some tuned percussion for the softer parts like the one around 1:30. The majority of ostinatos would work with strings too.

For some reason your post is difficult to read BTW: 

Congratulations in any case!

Kind regards,
Daniel–Ømicrón.

I think this is a really cool piece. So devastating and great use of microtonality to produce that special effect!

Concerning microtonality, I am not familiar with it. I guess only strings can play it? I see that the 9 accompanying parts never appear together, and some parts can be further segregated to different parts, for example the clash of chords in bar 103-108, part 2 can be segregated to different instruments (woodwind?). 

I think a timpani is a must for this piece. Do you also plan to add two pianos as percussion in the piece as used by Stravinsky e.g. in his Symphony of Psalms? Those strong and clash chords, for example the place mentioned above can achieve marvelous effect! Just gives the microtonal part to strings will be fine!

I am not a good symphonist myself so I can only give some slight advice only, sorry for that! 

Just a brief comment about orchestration - love the piece, think it's really cool. If it is to be for MIDI only, then I'd suggest a percussion orchestra (maybe some untuned as well?). Of course, digital percussion can do the microtones, but if it ever was to be performed with live instruments then I'd go with others and say a string orchestra is your best bet for consistency of microtones and texture.