Best USB DAC for under $1000

A used PS Audio PWD2 if you can stretch your budget a few hundred dollars.

if you have a few of the DACs you can bring them to one store and listen to them. Also, most stores will let you bring them home for a bit to hear them in YOUR system. I usually do that unless I know the store's system really good.

The Peachtree is a great way to go.
If you can stretch it a little bit, you might check out the BMC PureDAC.
The good news is, 14 years ago there was a huge disparity in DA performance. Now the playing field is largely even, and a $1,000 unit is better than the earliest $10,000 unit :)

Ifi Audio iDSD Mini will be about $1K.

The new and beautiful looking Marantz HDac1 (?) is $800.

I am waiting for a review to come out on the Marantz HDac1