Vocals sound different when played back on speakers, headphones etc
I recorded some vocals to a backing track in Garageband.
I am now in the process of tuning the vocals. Problem is, say I tune them as best I can then play them back on my speakers, they sound ok, but then if I played the exact same thing back on my headphones (or on the macbook speaker) they would sound out of tune. So I would then tune them when listening to headphones, only for them to sound out of tune when I play the song back on my speakers, and this just goes on and on. I'm just going round in circles with this, and it's driving me crazy.
Am I doing something wrong? What can I do to stop this? Does this have something to do with an audio interface?
Many thanks
GarageBand (Mac) '11, Mac OS X (10.6.7)