You made a good choice with the Presonus. It's the same thing as the
Alesis iO.
JMA, you have to specify Alesis M1 "Active" MKII Biamplified Reference
Monitor if those are the ones you want. Active means amplified. If you have no
onboard amp, you'll know it. I'd prefer left and right 1/4" out jacks to a single
headphone out. You get full signal per channel and still get to plug in phones.
What happened was that the computer manufacturers originally wanted to
build preamps and digital converters into the laptops. The recorder manufacturers
raised a ruckus & put it to them, are you building computers or audio recorders?
because if you are building audio recorders, here's a long list of regulations
you will have to comply with, just as we do. It didn't take much convincing.
The result is that we need an audio interface to do serious recording.
It converts analog to digital and pre amps the signal,as far as I know.
I'm no engineer.