The Pro-ject Stream Box S2 Ultra is a terrific value for price-performance. What it is NOT is the complete system that BluOS is for expansion into multi-point access to music in the home (without a Roon subscription.)
The DAC in the Oppo players is a very good ESS Sabre. The DAC in most Bluesound Node, Vault, and Pulse players and speakers is a very good (but different) Texas Instruments Burr-Brown PCM5122. They are both good, but there are subtle differences in presentation.
KEF R500, R200C, R100, R50, SVS SB2000 sub, NAD T758v3 AVR, Pro-Ject RPM1 TT w/ Ortofon 2M Red, Bluesound Vault2, LG UP875 4K BlueRay, Samsung UN55JU6500F 4K LED TV, KEF M500 headphones, Sony CDP-CE500 CD changer. Desktop: NAD M10, KEF LS50, KEF Kube 10b. Guest room: Hafler 200 L-R, KEF reference Model 100 center, KEF iQ10 surrounds, M&K V-90 sub.