If you're aware of the MUTEC MP3+ USB external clock and SPDIF converter, nothing more needs to be said. For those who aren't, it's a world class external clock that both improves the clock of your current DAC or clock dependent digital components (e.g., Etherregen) and enables you to improve/add digital SPDIF capabilities to your system. Considering the prices of external clocks, it's an amazing value at $1199 new. I'm selling a virtually new one for $875 shipped. It's about three months old and barely used, as the photos will attest. If you need more info, rave reviews are below. Including one from right here at Audiophilestyle.

I'll pay for shipping. Buyer is responsible for extra insurance and any transaction fees, although I do accept PayPal friends and family

https://andreweverard.com/2016/07/12/review-mutec-mc-3-usb-clocking-the-best-way-to-improve-your-digital-audio/

https://www.mutec-net.com/artikel.php?id=1489107561

https://6moons.com/audioreview_articles/mutec/

https://hifipig.com/review-mutec-mc-3-smart-clock-usb-master-clockreclockerspdif-converter/