should I go with the rega brio or schiit vidar

The Rega Brio is an integrated amp so you can use it for line stage and amp. It's received lots of positive feedback, however, with your Oppo you have an opportunity to run balanced with XLR. The Vidar provides an XLR balanced input so if that is important to you I would look to the Vidar (assuming you can use your Oppo as a line stage.)

Both the Rega and Vidar can be had for less than $1K. How far under $2K are you looking to land? You still may have room in your budget to research other options...

Just looking through integrateds, amps and preamps in the Audiogon marketplace, you would certainly have some options in the $1K-$2K range. If you like Rega, there is an Elicit-R in the $1,600 range which should get you a few steps up in the Rega line (no affiliation to seller, just an observation during a quick search.)

I'm sure you will receive some good recommendations from the community. 

Good luck

Just look at the Nuforce sta 200. Class a/b originally $1400 now $499. Just try it. Great reviews designed by the same Goldmund team that gave us the JOB 225

https://www.amazon.com/NuForce-STA200-160-watt-Power-Amplifier-Swiss-design/dp/B01552AKCU

I agree with asp307. Many options available within your budget. Are you looking for a integrated amplifier, or can the Sonica be used directly into an amplifier? My bias would be toward using the Sonica with fixed output into a integrated. There are those who would suggest using it's variable out.