You beat me to mentioning the sheer size of those libraries. If they reside on multi TB SSDs connected via Thunderbolt, taken along for the tour, i can easily imagine, that a Mac mini would a good solution. Apple embraced Thunderbolt early, it was even exclusive to them IIRC. If i were responsible for playing those sounds, i would want one stable platform too, instead of several diverging implementations on standard pc hardware and the fun (/s) that i'd have (drivers, windows updates etc...).