If you can, ditch AverMedia. They produce starter-grade gear. The U3 is also known for its finicky nature. If you can, look at a Micomsoft SC-512N1-L/DVI capture card. $330 from Solaris Japan, but SabrePC is selling one for $100 cheaper that doesn't come with the passthrough daughtercard (big whoop, use splitters or just play on the monitor).

This is hands-down THE best capture card for livestreaming, at present. 0-2 frame capture delay, can accept almost any input you throw at it (240i to 1080p@60, so you're covered from the oldest retro consoles to the newest gen stuff). Only thing it doesn't do is strip HDCP on-card, which can be handled with a few specific $20 HDMI splitters on Amazon.
This is what I use, and if mine ever broke, I'd be buying a new one less than five minutes later. It's truly an awesome card. I just play right on my monitor, using AmaRecTV 2.20c, and capture that in OBS (to avoid the extra delay by capture/scaling/compositing in OBS, though I was playing on the Projector Mode before, it's closer to a 1/10-1/4 of a second delay that way). Here's a link to a capture delay test video I did, to demonstrate just how FAST it is.

I use the non-effects version of that mixer, the 1204USB. It's a very solid piece of gear, and produces good audio if you take the time to set it up properly.

The AT2020 is a solid mic, but the AT2035 is just a bit more expensive, and is a significant improvement (if you can, the AT4040 is better by a much wider gap, but doubles the 2035's price). Do be aware that as these are very sensitive, and will pick up a LOT of ambient noise. You might want to consider looking at headset or top-boom shotgun mics instead, if possible.