What is the best usb convertor


I have a number of DACs ,Zanden,Accuphase 800,which do not have USB inputs I would like to purchase a USB convertor that I could use with my DACs.Any recommendations.
ramy
I use the Berkeley Alpha USB converter and am quite happy with it. I get sound that seems a worthy alternative to my LP rig.
I really like the v-link, but it's discontinued, but you can find new product on eBay.

Regards.
The V-Link serves well and is inexpensive. I bought a Link II on AG for $70. I find several on E-bay at $100 or less. I have an Audiophilio 2/Purepower in my main rig. That combo is better however at ~5x the price on the used market.

The V-Link represents great value.
If I needed one, I would try the Empirical Audio Off-Ramp. It has lots of features and options. If you don't like it, they give a full refund.