Firewire interfaces can and will blow up if you plug or unplug them while the interface is on. Especially Saffires. Trust me, I've done it!
Also, in response to JohnnyV, phantom power shouldn't ever apply to true line inputs. Instrument inputs will receive phantom, so it's important to know the difference, especially since they look the same! All the old/vintage consoles had global phantom power, you couldn't even turn it off if you wanted to. Contrary to popular belief, dynamics and ribbons are fine with phantom power (with the exception of ribbon mics when patched through non-XLR patch bays)
I don't think you can blow an input by turning it up too hot, it just clips.