Multiple Roland synths as USB audio interfaces.

I think you need to decide what you want each of the keyboards and the DAW to each be doing?

Are you trying to send midi in from each to the DAW. Do you then want the DAW to record the midi? Do you want the DAW to be sending midi from the DAW to play on each keyboard? Are you going to create the midi data on the DAW or on the keyboards?

Same sort of questions should be answered for audio signals?

Where do you want the sounds to come out? From each of the keyboards producing their own sounds? Or from the laptop/computer? Where/how are you going to mix the 3 sounds? Where are you going to send the final sound....do you have amplifiers/speakers?

Will you be using microphones for voices or other sounds?

Have you looked at the Roland MX-1 Performance mixer and audio interface...which has dedicated USB inputs for Roalnd synths which handle midi and audio IN and OUT? It is also a Performance Mixer lets you manipulate the sounds with added effects beat by beat?

Would not recommend all 3 direct into the DAW. Probably would work but its no real solution. Decide first what you what to do with all the kit and how you want to use it....then perhaps others can help you select best way forward for you.

Good luck.

I'm kind of curious if I could purchase two Roland UA-25's and use both together on the same PC at once or how that might work. I mean it may in fact work, but could have limitations like moving any software control parameters on one links to both devices and anything connected to those I/O parameters and shares control over the results.

I'd be fine enough with that to be fair though because I have a very symmetrical hardware setup of devices 2 RM1x, 2 MC-808's, 2 DTXpress III's, and a few solo hardware synths atm though that too could change. My goal is kind of of synth hardware based DJ battle mixer kind of setup between pairings of synths a different twist on the same general idea.

One thing I don't like about most actual DJ mixers is the vast majority all use RCA connections it's hard to find any with TRS inputs/outputs which I don't at all understand how there aren't a few around that are more prosumer studio quality designed in mind. I don't think it's a big issue with short cable runs though, but the peace of mind of it bothers me personally. I did notice the DJ-808 has a 4-coxial inputs though and that's awesome you could pair 4 of the XV-5080's into it like holy crap that would just be insane with the sequencer built into it. I don't know if Serato and like these days has direct MIDI file support or not, but I'd be keen to know if it does because it defiantly should you're play set would never be the same again.