I'm using a Mac Mini with lower specs here for testing/troubleshooting Band-in-a-Box, and I'm pretty impressed with it.

This is a 2014 model, 1.4 GHz i5 with 4GB of RAM, and it performs much better than I would have expected, though it's only used for BIAB, so I haven't pushed it by doing any multi-channel audio recording in a proper DAW or used many plugins at the same time.

I'd say a 2.6 GHz i5'll run nicely, and will handle BIAB and most DAW work without breaking a sweat.

Thanks
Kent
PG Music