Teach me about my acous/elec + acous amp!

OK...I've got my Taylor 614CE with the electronic and just arrived, a used Fender Acoustasonics Jr off Ebay.

Sooooooooo.... first noodling yeilded much feedback even at low volume. What's the proper way to adjust the settings on the Taylor (it has an internal mic and a piezo with a balance control). It's got a notch control, treble, bass, loudness and phase switch.

On the amp (nice little amp), it's got two channels and has a notch control, reverb, chorus...etc.

I'm an ace at dialing in electric sounds on any amp but this is new to me. How does one start getting a decent sound. How/When to use these other controls?

PS - the Variax sounds nice through it also (and no feedback!!!). I've tried the XLR and regular outputs...they sound similar. I'm thinking it might be cool to run acoustic Variax sounds through the XLR and the electric sounds through a little effector or my Fulldrive 2 on the other channel. It's not really an electric amp and doesn't distort nicely but it does work with a pedal as long as it's not too loud.

I'm guessing it's the internal mic thats howling.Set all controls flat(at guitar & amp) & turn off all effects.Set the balance to full piezo then blend in the mic,then tone controls & finally effects if wanted.Just a thought.This should show where in the chain the problem is.Actually, the phase switch should
reverse the feedback signal and quiet things down.

The key was really turning down the internal mic and mostly using the piezo bridge pickup. Sounds great through the Acoustasonic!