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Please update your signature (see link in mine below) with your systems specs as that helps in responding to your questions.

Yes, the MIDI In/Out and the Line In 1 & 2 (1/4" jacks) on the Revelator io24 all work as expected.
I connected the MIDI and the L/R audio output connections on my Roland SC-8850 to the MIDI and Channels 1 & 2 connections on the Revelator io24. I set it up in Studio One 6.5 as an External Instrument and Aux channel. My Nektar LX61+ keyboard works great with it.

The Korg Modwave should work fine with the Revelator io24.

Here's some good video tutorials specific to what's required to check out:

Just some thoughts:

First of all your synthesizer must have a midi interface. If it does then that interface will send your keyboard strokes from the synthesizer to the computer, not the synthesizer sound. And the computer can send (recorded) keyboard strokes back as if you were playing the synthesizer's keyboard yourself. So Studio One will communicate with the keyboard of the instrument, not with the sound part. That way it doesn't matter if it's a synthesizer or a digital piano or whatever

Well this sucks. Its looking more and more like its defective and I got this quite a while ago so I doubt i can still take it back. Ive plugged every synthesizer out to every audio interface in. Studio One aside - the interface should at least be showing bars when connected via stereo and headphone, correct? So i can at least know if the problem is on the hardware or software level. Cause I did do everything these videos told me to but if the audio interface isnt showing bars I doubt anymore messing with the DAW will solve the issue. But I turned the local control off, i set the global channels right, I added the names as external MIDI both what my PC identifies it as and the name itself. My pc sees it as KORG 'modwave1' but i also tried KORG 'modwave'. That to me is kind of weird its supposed to identify just on the make and model, id expect it to look more like a plugin but i do have all those installed. The modwave does interface directly with my PC via modwave native but i want to both use different modules and capture the sounds i have on my synth. My synth headphone out and stereo out both work in my amplifier which is why im expecting to at least the bars light up on my audio interface. If this is defective please be honest so i dont keep wasting my time on this. This is a headache and has taken many of my hours. Thank you very much for the helpful responses. I wasnt set up for midi via DAW and i still may not be doing that part right but I should at least see the revelator is at least identifying something is sending signals to it id imagine if not midi at least stereo and headphone. It does send audio from my pc to my amplifier just fine oddly enough and so can my synth.

Please post screenshots of your mixer in UC Surface, your I/O and also your synth settings in Studio One External Devices.

Here's a diagram for how everything should be connected.

Okay, in that diagram it looks like theres a fourth thing on the right the audio interface is hooking up to. Before i go further cause theres a whole lot of questions I have and a lot of screenshots to take cause ive gone through a whole bunch of different settings but the names of the outputs and inputs dont match the audio interface. I see mic/inst stream mix and virtual output and CTRL in and CTRL out and all the outlets on the audio interface just say MIDI and L/R and headphone none of them match with what i see in the daw. I see modwave1 (the virtual synth version of modwave) as an input/output option in audio i/o and i see revelator midi out and midi in and ctrl out and ctrl in and ive tried every combination of that. To me, it looks a whole lot like this is just for sending sound from pc to the audio interface and I want to quickly clarify before proceeding that im trying to get the audio interface to capture the sounds my synth is creating and feed it to my pc so it can be recorded there. It doesnt seem like this synth has a record option on it. So being able to play a virtual synth and hear it through my modwave is cool and id like to learn how to do that as well. For right now im trying to get the audio interface to send the sound to my PC but its just hooked up to my pc through the regular usb c/usb regular and im not sure if I sound ridiculous thinking i can do that or not. Again the revelator bars light up when i play sound on my pc. However all the bars are completely dead when i try to hook it up via the 1/4 audio jacks, ive tried regular L/R stereo lines and TRRS, This synth can play through my guitar amp on the 1/4 jacks but the audio interface is really not giving any indication that its recieving anything and thats just a small part of the equation cause after it does recieve the sound i also need to be sure it can actually send that to my pc through just a regular usb cable. As for the two front facing plugs I dont have those, not sure if id need them and to clarify - these MIDI cables do not transmit the synthesizer's sound only keystrokes and controller data? Thank you.

ConnellCook wroteOkay, in that diagram it looks like theres a fourth thing on the right the audio interface is hooking up to.

That's showing how to connect the io24 L/R audio outputs to powered speakers.

ConnellCook wroteBefore i go further cause theres a whole lot of questions I have and a lot of screenshots to take cause ive gone through a whole bunch of different settings but the names of the outputs and inputs dont match the audio interface. I see mic/inst stream mix and virtual output and CTRL in and CTRL out and all the outlets on the audio interface just say MIDI and L/R and headphone none of them match with what i see in the daw. I see modwave1 (the virtual synth version of modwave) as an input/output option in audio i/o and i see revelator midi out and midi in and ctrl out and ctrl in and ive tried every combination of that. To me, it looks a whole lot like this is just for sending sound from pc to the audio interface and I want to quickly clarify before proceeding that im trying to get the audio interface to capture the sounds my synth is creating and feed it to my pc so it can be recorded there. It doesnt seem like this synth has a record option on it. So being able to play a virtual synth and hear it through my modwave is cool and id like to learn how to do that as well. For right now im trying to get the audio interface to send the sound to my PC but its just hooked up to my pc through the regular usb c/usb regular and im not sure if I sound ridiculous thinking i can do that or not. Again the revelator bars light up when i play sound on my pc. However all the bars are completely dead when i try to hook it up via the 1/4 audio jacks, ive tried regular L/R stereo lines and TRRS, This synth can play through my guitar amp on the 1/4 jacks but the audio interface is really not giving any indication that its recieving anything and thats just a small part of the equation cause after it does recieve the sound i also need to be sure it can actually send that to my pc through just a regular usb cable..

I posted links to video tutorials specific to what's required and a diagram for how to connect your synth to the io24 in my previous responses. Based on your review and implementation using those resources I still need screenshots or a video from you showing how everything is connected and configured. Often that helps in identifying why it's not working.

ConnellCook wroteAs for the two front facing plugs I dont have those, not sure if id need them and to clarify - these MIDI cables do not transmit the synthesizer's sound only keystrokes and controller data? Thank you.

For audio you definitely need to connect cables from the 1/4" L/R audio outputs of your synth to the inputs located on the front of the io24. Yes the MIDI connections are for sending/receiving keyboard and controller MIDI (not audio) data.

Oohhhh!
Okay. So all the plug ins on the back (L/R Main, headphone, MIDI) except for the MIDI IN that are on the back are OUT only. That makes sense, I feel dumb now. So I need to have something plugged into this weird plug to send sound into it. Ive never seen or used this type of plug before so my next step before messing with the daw should be to find i guess itd be like two 1/4 stereo L/R that change into these plugs? Or an adapter or something? What is this plug in even called? Well. Oddly enough while I was at work I had an idea that I thought to myself might be stupid enough that it just might work. I plugged a 1/4 jack from my headphone out to my amplifier and then plugged one of those printer usb cables into that and then into my PC. Definitely not expecting it to work, figured id need to download a bunch of drivers or software or something but nope. Weird enough, boom. There it is in audacity recording and everything. This to me is so weird. Why can I play sound to my PC using this janky method but cant just plug my synth directly into my PC? Obviously, youre not Korg. Just seems like they couldve done more to allow users to at least if not record on PC at least record on the synth and put it on a usb driver or something. But my next step should be to go locate the right cables. I dont think i can use my amp as a long term solution. The sound settings are made for strings and it doesnt have L/R input.

MIDI is not sound. Your computer put you on the wrong foot there.

MIDI OUT on your synth sends information about which keys you're playing, how hard you hit them (velocity) and how long. Via a MIDI cable and a MIDI interface Studio One can record this info on an instrument track and send it back to MIDI IN on your synth, which will make the synth play as you were playing it.

To hear what you're playing inside Studio One you have to drag an instrument plugin like Presence or Mai Tai onto the instrument track. That way you can turn the keystrokes into piano sound or clarinet or whatever. So instrument plugins turn MIDI into sound.

Your computer's media player must have a default instrument plugin it uses whenever MIDI is received/played. That made you think that MIDI is sound, but it isn't