I understand how a flat maj 3 chord could be borrowed from the parallel minor key, but how could a maj 3 chord, say G# maj in key of E theoretically work?
It contains a #5 (of the E major scale!), so if you want to justify it with some kind of theoretical backing, you're briefly transitioning into or borrowing from E Ionian Augmented (1 2 3 4 #5 6 7).
It's not the baroque era anymore. If you can break the rules to create something new that's dissonant but at the same time sounds good ... good job. Although, G#maj in the key of E major isn't THAT dissonant.
All you need is to make it sound cool and you have justified it.

Keep in mind theory is "retrospective observation" in as much as it helps us understand what has been done before and why it worked. It's not a governing piece of legislation that describes what will and won't sound good.

But in answer to your question, you could consider it a secondary dominant of the vi chord in the key of E.

EDIT: I just made a cool progression (at least I think it's pretty cool) using the G# in E as a functioning secondary dominant.

E | G# | C#m | A B | E

I wonder what I can grow out of this seed?
Last edited by 20Tigers at Dec 11, 2008,