I used this with my AT2020 for a 6+ months, but as I become more knowledgeable about the equipment I was using, I realized that the phantom power the 502USB provides just isn't adequate

Its doesnt have enough phantom power.

Why does an audio mixer need to use (and waste) that much power

The only negative is the lack of an on/off switch, but it is powered into a power strip, which supplies the on/off function, so no worries there.

Everyone uses 48v) and a weak power connector

15v Phantom power. if you have a powerful mic and external FX board that will tie into the 502, the phantom power is not enough to support it

At first it seemed like it was powering my AT2020 just

Phantom power on this unit is not strong enough to drive my microphone

I'm not sure if my mic just isn't getting enough power or what

My only complaint would be no power on/off switch

The included phantom power is a bonus for my mic.