whats is the best usb to xlr converter

The best converter will have the most sonically pleasing overall jitter, which means expensive master clocks and power regulation. It's impossible to achieve zero jitter BTW, even though some marketing will claim this. Making a decision based on jitter measurements published by marketing teams is frought with problems. Even the best direct jitter measuring equipment does not take jitter measurements in the "system environment", so this can make a huge difference in the performance of a converter. There are also at least half a dozen ways to characterize jitter, making it impossible to compare apples-to-apples.

As with all electronic components, the price may not be the best indicator of performance, but it's usually a good place to start. Second, read the reviews and determine how many world-class reviewers use it daily. Look for shootouts.

Steve N.
Empirical Audio

hi sorry its not to xlr it is to spdif

There is no definitive "best" of anything. There are way too many variables involved. The "best" you can hope for is to find something that works well in your system. You can then say it's the "best" for you until you find something you think is better !!!!