Seems the HW is there to create a Send/Return for effects to do things like assign the stereo mix out to 1/4" pair to an effect unit and back to an input pair to be mixed into the main mix.
Also, while on the topic, what are some effect units that would be great to pair with the S2400? The Kaoss Pad KP3+ looks like something that could add some dynamic fun to the S2400. IO is only via RCA jacks, but that is easy to move past with some adapters.
Would love send return
+1 for assignable send return that would be awesome!
This is a great suggestion
i have asked, asked and asked
seems no desire for it
you can do something like this but via live loops but is a faff
I would kill for this to be implemented in an intentional way. The live loop option does work but not super intuitive.
There is no way to “assign” anything to the mix out. The mix out is a hard-wired mix of the signals from the switches on the eight individual output jacks. The only software control we have over the mix out is a balance control for sending each of the eight signals to the left and right mix outs. They cannot be muted. The only way to exclude an individual out from the mix out is to insert a plug into the individual out jack.
Thanks Mickey, that makes sense.
Any smart ways to route audio out and back in to get to the main mix?
Anything smart that can be done with the USB audio? I’ve been loving having an iPad plugged into the device. If I could use audio bus to take output channels from the unit through AU effects and back into the unit to get mixed in with the main out, that’d be magic too.
Maybe this could help out?
I have not tried it myself, but my guess is that this post was done by @j.m (not sure though)
it’s me Syah 
crazy that nobody else has found this yet - or maybe my machine is a unicorn 
What??? How do you keep the signals in the main out and still have an individual output plugged in?
Shift + pad and then what?
This is news to me!!
@Melkerpetterson i could load video to show you but it is easy enough to achieve
insert some indi outs and send them somewhere
connect stereo out
shift+pad and select stereo (using L,R or L+R stops the stereo mix receiving audio which is expected)
use stereo samples and observe your mixer - in my machine it is not an either/or situation, it is parallel at all times
either the machine is doing some weird stuff with the file or the HW is doing something they did not expect - FTR before anyone gets pissy i am not seeing this as a negative, the contrary in fact
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something that i don’t understand is why my main mix goes a tad quieter at the point i insert cables into my indi outs - there is clearly some weird HW interaction there and i do not see this on any other gear i own and i use indi outs on a lot of stuff, i would appreciate someone actively plugging into indi outs while their stereo mix is audible and running to see if they hear a change in output too - thanks
Interesting!
I’m I understanding this correctly: You have to use stereo samples and set the playback to stereo? Then the sample will play out the individual outputs (when cables are there) and play out the main output as well?
it does on mine
Ahh was wondering what you were referring to/ how you did this when you posted on GS. I have come across this behavior. I’ve chalked it up to “half” of the stereo sample playing out the individual out and the other half playing out the main mix because only 1 indi out was connected (ex. stereo sample on channel 1, and only ch 1 indi out connected instead of 1+2). Happens with mono samples also when set to stereo. Given that example I believe if you were to plug a cable into out 2, it would cut from the main mix.
yeah i thought this which was why i said something weird may be happening with the file
it seems to flip the polarity of the indi out too , either way it allows audio to be sent elsewhere even if it is a jack way of doing it
yeah i remember playing around with this a little while back when i first got one of those Per4mers. I was sending a piano sample out into the fx unit then into my interface which worked as expected. Only thing though was when I wanted to send the new wet signal back into the 2400 it became doubled/feedbacky and the wet was also further diluted since half of the original signal was playing out the mix out, so still working out a good process for send > return. I’d likely just record the wet signal into a live loop then cut the sample track off altogether
Not sure if this has been mentioned elsewhere, but if you go to input monitoring and switch on “only usb to jacks” you can achieve this. Right now I have the 8 outputs assigned in audiobus/aum and add auv3s to the channels I want accordingly. I haven’t tried resampling back into it, but saving presets in aum allows me to quickly recall what I had effects wise for each project. I also have some ipad synths running through the S2400 at the same time as well.