Also use the Guitar Tricks reference tuner to get yourself close to being in the correct key by ear. Assuming the Snark was on the correct setting, then you'll be close enough to use the Snark to fine tune.

I use this reference tuner when I change strings to get me 'in the neighborhood'. Even though I can pretty much get there by ear, why do it the hard way? Also, getting close to the correct tuning by ear is a very handy skill for a guitar player.