I am someone who uses multiple computers in my studio. 4 in fact. (3 Windows machines and one Mac) Firstly to the non believers, the end result is much more than the sum of the parts. No single computer can compete with multiple computers, end of story.
I am on Studio One but I only use one machine to do all the sequencing. That is important. Two of them do virtual synths and the fourth often doing a classy reverb etc.
The way I have got them all connected is via audio and midi. I have got audio connected via analog and digital in both directions between all machines in fact. I find it is the best way to do it.
(I do have a Yamaha digital mixer which brings all this together rather well, analog and digital audio all at once) Two of them are networked and there are some free Reaper plugins that allow you to send audio (and midi) via the network and back. It all works great except the network takes about 5 to 6 ms in latency including return latency. So I just adjust those tracks to play about that sort of time early and they all come out in sync.
You need a mixer to combine the audio outputs from the other machines. I turn all that into audio in the main machine just before the mix.
It is quite cool. One of my machines is a 32 bit machine running all the plugins I cannot run on the 64 main machine.
I like the way the 4 machines can go off into different directions and do different tasks but for a big session they all come together as one. I find the main machine can relax a little and is not strained in the least.
Like I said no one single computer can come even close to this. It is amazing. You just need to have the computers to do it that is all. It is the equivalent of about 12 cores or more.