The only benefit you would get from reducing vibration to the Mac Mini would be to reduce vibration going to the hard drive--to prevent it from failing. However, as others are hinting with a cat analogy, if the hard drive can read the binary content (1s and 0s) you get your sound and it will be exactly the same.
Arguably, at some point vibration would make the Mac Mini's hard drive not function. But, at that point you wouldn't get sound at all.
Don't believe me that there's no audible difference in isolating a computer? Blindfold yourself and have a friend shake the Mini whilst playing a file and not shake it. Literally, shake it (but don't brake it). You won't be able to tell a thing. It's 1s and 0s.
Again, I do think you could make the argument that you don't want it vibrating because you don't want the hard drive's working reading mechanism (an arm) to slowly move out of alignment and fail. Yet, I would think that you would need a ton of vibration to make it fail or even skip.
Finally, the saying that anything with moving parts needs isolation to sound good is not correct. A phono cartridge will pick up vibration and it will effect sound. Loudspeakers arguably may lose focus if they are vibrating greatly. An amplifier? Now that's a stretch. Someone would need to explain why an amplifier's sound would be effected by vibrations. If you believe this do you also believe that we should isolate our plasma or lcd televisions?
PS Most hard drives and the software running them have giant buffers and error correction. This prevents you from noticing any problems if the hard drive skips or cannot read a section of 1s and 0s.
