Ok, I’m new, and really good at overthinking things, so I need some help.
I have the Play, and just ordered the Synth. My desired set up is to connect the synth and the Play together, and have them talk to an eurorack (currently just the East Beast).
So, I guess my question is, is this possible, and what hardware am I going to need to invest in?
Also, what is the best way to get the audio to a single output? Meaning audio interface, external speaker etc.
Thank you in advance for answering my stupid questions.
Hey @devonsemail2.0, welcome to Backstage! 
There are no stupid questions! 
Regarding MIDI:
In order for the three devices to talk to eachother it is probably best to get a Midi Thru Box (that will also serve you well in the future).
Something like:
There‘s a lot more of these types of boxes out there, but these are very good value for money.
You could technically connect the Play → East Beast → Synth .. as the East Beast has MIDI In and MIDI Thru. But it uses TRS-A MIDI while all Polyend devices use TRS-B. Which means you would have to get two converters.
My recommendation, get one of the CME boxes and then you don‘t have to worry about that, since you already have all the DIN to TRS adapters that you require from all the devices.
Regarding Audio:
If you want to sum things up, a small mixer with atleast 6 channels (each stereo pair = 2 channels) will get you there. Or do you already have a audio interface with atleast 6 channels?
It really depends what you want to achieve. If you just want to get everything to a speaker and don‘t care about having recordings of each individual channel. Just go for a mixer. If you are planning on recording things into a DAW for further processing. You should probably get a audio interface with enough channels.
If you let me know what your goals are, i can give you some more detailed informations.
But this should give you already plenty to think about 
Sorry for the late response, busy at the day job. Please explain to me like I’m 12. Why would I want to use this stereo to mono splitter instead a single stereo cable?
That purely depends on where you are sending the audio to:
Most audio interfaces and/or mixers usually have mono inputs (unless noted otherwise), which means you must split a stereo sound into two mono channels (left and right).
If the device that you are sending the audio to has a stereo input, then you don’t need the splitter.
Ok, now I understand. I come from a video background, so a lot of this is very new to me.
Thanks.
All good, if you got more questions - just let us know. Happy to help
It’s going to be a hot minute before I can afford a 6 channel interface. Unit then, could I use my 4 channel, and duplicate the tracks in my DAW? Or is that not how things work?
Oh yeah of course you can! The 6 channels is only if you want to record every single audio channel at the same time / in one go.
As a cheap alternative, you can always get a summing mixer (Behringer Xenyx Series or Mackie Mix8) and put everything through there. Then record the mixdown from it into your DAW.
If you are ok with recording each instrument individually, there is nothing stopping you from recording 2 or 4 channels at a time. Whatever works best for you and your flow.
