How to use two computers simultaneously for production (CPU sharing)

Question

I am investigating ways to use two (or multiple) computers simultaneously for music production, for either Ableton Live or Apple Logic.

The main reasoning behind this is CPU sharing. I have two Macintosh computers, and I would like to make good use of both.

The topic of my question, thus, is not about sharing MIDI or syncing projects, but rather to seek out ways that could enable me to utilize two computers' computing power.

Some ways I can imagine it happening

1. Daisy-chaining/sharing CPU power between the computers, for use in one DAW (Something like the legacy Logic Node software that was discontinued?)
2. Using two DAWs on two computers, each of them using different tracks but playing on the same MIDI clock, and then sending the output to the master computer as a VST stream (something like Vienna Ensemble Pro – an expensive VST software).
3. Using two DAWs on two computers, each of them using different tracks but playing on the same MIDI clock, and then render both their audio outputs to one track in a real-time mixdown.

The first solution would probably be the most preferred, and the third would probably be the least preferred.

Question

What are the possible (and preferential) solutions out there? What is the most viable solution? Is there a "free" technical solution that doesn't depend on expensive software like Vienna Ensemble Pro?

Answer 1

Vienna Ensemble Pro

Take a look at Vienna Ensemble Pro (VEP, VEPro). There is a Master/Slave feature that let you process VST instruments (and ordinary VST effects) on other computers (and you can mix Macs and PCs).

The master sends MIDI commands to the slave, and the slave returns the result samples. All through a plain cabled ethernet connection.

Here is their own description (from below video):

Vienna Ensemble PRO is the first MIDI and audio LAN solution that works universally on Macs and PCs, hosting Vienna Instruments as well as 3rd party 64-bit and 32-bit VSTi/AU plug-ins. Use it as a master-slave solution with multiple Macs and PCs, all connected with a simple Ethernet cable, and route the audio streams back to your main machine without the need of further audio hardware. The intelligent Preserve function enables you to keep your instruments loaded while switching from one project to another and with the 64-bit version you can load as many samples as all of your RAM will hold.

Take a look here (good stuffs around 1 min in..):

Cubase VST System Link

VST System Link allow you to run a complete slave host on other computers, which means you're not constrained to VST/VSTi processing. It is however Cubase only and it may require an additional license. Here is the description (taken from this document):

VST System Link is a network system for digital audio that allows you to have several computers working together in one large system. Unlike conventional networks it does not require Ethernet cards, hubs, or CAT-5 cables; instead it uses the kind of digital audio hardware and cables you probably already possess in your studio. VST System Link has been designed to be simple to set up and operate, yet give enormous flexibility and performance gains in use. It is capable of linking computers in a “ring” network (the System Link signal is passed from one machine to the next, and eventually returns to the first machine). VST System Link can send its networking signal over any type of digital audio cable, including S/PDIF, ADAT, TDIF, or AES, as long as each computer in the system is equipped with a suitable ASIO compatible audio interface. So, why would you want to link up two or more computers? Well, the added computer power gives you vast possibilities:

• Dedicate one computer to running VST instruments while recording audio tracks on another.
• If you need lots of audio tracks, you may simply add tracks on another computer.
• You could have one computer serve as a “virtual effect rack”, running CPU-intensive send effect plug-ins only.
• Since you can use VST System Link to connect different VST System Link applications on different platforms, you can take advantage of effect plug-ins and VST instruments that are specific to certain programs or platforms. This chapter describes how to set up and use VST System Link in Cubase SX.

Answer 2

There are some producers that use a setup similar to the one described. Junkie XL seems to run VST from separate computers using Cubase.