FWIW, the Pro-ject Stream Box sounds quite good. I haven't listened to too many higher priced streamers, but I listened to a $7500 Naim NDX 2 as a streamer feeding my Pontus II DAC and without comparing head-to-head, I'm not sure I could confidently say whether the Pro-ject or the Naim is better sounding. I do like for a budget component that the decision was made to not include costly features such as a built-in DAC or LCD screen & that effort was focused on reducing sources of electrical noise. Some details about the design of the Pro-ject from the designer are in this thread:
https://www.avforums.com/threads/why-is-pro-ject-stream-box-ultra-s2-so-expensive-700euro-for-an-r-p...
https://www.avforums.com/threads/why-is-pro-ject-stream-box-ultra-s2-so-expensive-700euro-for-an-r-p...