Hi,
We are running 8 Mac Mini's here ("somewhere in Los Angeles" [:)]) with the full library (Orchestral Cube) splitted between all of them. My answers below are thus based on real-life tests and experiences.
Yes, the Core Duo IS totally worth the extra money - it reaches the performances of a Dual 2.5Ghz G5!
I highly suggest an external drive or - better - replacing the internal drive yourself with a faster, 7200 rpm, 100GB drive. FireWire drives are still IDE - no comparison with an internal SATA drive. And the better drive, the more polyphony you will get.
Also, and obviously, you *need* 2GB of ram (especially if your goal is to use as much power as you can from these little babies).
The great thing about the Mac Mini's is their Optical S/PDIF I/O. However, to my knowledge, there are no audio interface that offers 8 optical (or coaxial, if you used a converter) S/PDIF I/O. So, we went with a set of products from
Friend-Chip: One DMX16 (frame + motherboard), on which you add two ADAT modules (MQA) and two Optical S/PDIF modules (MOP4).
Basically, the box converts the 4 optical S/PDIF I/O to an 8-channel ADAT stream.
Then, you can plug the lightpipes cables to any ADAT interface. We use MOTU 2408s because our sequencer is a Powermac Quad, and that is the best (if only) PCI-Express solution available at the moment for this specific use.
Until the
M-Audio ProFire Lightbridge comes out, the Friend-Chip seems to be the only solution.
We tried Wormhole. It's a neat piece of software for small/consumer use, but too unreliable to use in a professional studio. Also, customer support is nearly non-existant (check out their message board to get an idea), and this is not something we want to have to deal with.
Besides, Wormhole goes throught the network and we are already using it for large file transfers, so we would have had to get a separate network just for it... So, as you can see, Wormhole was definitely not worth it in our case.
We have *both* Apple Remote Desktop and a KVM switch. Since all the samples are loaded in memory once and for all (more on that below), there is no reason to access the VI UI once everything is setup. So, there is no real justification for a second keyboard and mouse around the writing station. Thus, we use ARD when small issues happens and, for example, we need to fix a matrix, or quit Plogue Bidule and relaunch it.
In specific cases (troubleshooting, installing updates, samples, etc.), we use the KVM switch, which is in the technical room, right above the 8 Mac Minis, with a 15" monitor and a keyboard on a sliding shelf.
In regards to the Sequencer, we use Logic with a highly customized environment, based on John Frizzell's. The goal (and the great achievement) is to have only one track per instrument, and to switch articulations by selecting different channels (via a software or a hardware controller). Then, transformers transform (duh) the channels into controller messages, so that the VI engine can switch cells on the fly.
Not only do you avoid any keyswitches this way, it also produces a midi file ready to be used in any notation program, since one track = one instrument with various articulations. And, maybe even better it gives you in the sequencer a track layout that *looks* like a score layout. No more "violins pizz" track, "violins staccato" track and "violins legato" track! Everything sits in the "violins" track.
To come back to the Mac Mini's, in regards to performances, we are still in testing phase, but for now we are extremely pleased with the results. We can get a very, very high polyphony - basically higher that what anyone would need in a real-life situation. Moreover, you know that if the Mac Mini's run fine separately, then all of them, playing together, will run equally fine.
In the end, it is better performance-wise and cheaper to have VI running on eight Mac Mini's than on four 2x2.5Ghz G5's with 4GB of Ram.
Yes, it is still an expensive solution. But, when considering the benefits (the whole VI orchestra loaded in the background!) and ease of use, it's absolutely a must have.
Now, everybody has different ways to work, so ours might not work for you. For example, we didn't try this whole thing in Digital Performer (or in any other sequencer). But hopefully my post will give you an idea of where you can go with this concept.
Jerome