Honestly, this whole DAC "upgrade" thing seems a bit useless to me. You already have a Pico... do you really need to go balanced with a middling budget? Especially with that laptop.
If I absolutely had to have an uber DAC via laptop, I'd probably be using Squeezebox as transport. Used ones are only in the mid-$100s these days. I haven't seen too many jitter figures for USB->SPDIF things, but the jitter figures I've seen for Squeezeboxes are pretty good. I'm gonna talk entirely from my ass and guess that Squeezebox should be better than a USB converter.