Thought this might be a job for an LLM, but of course suggestions without validation.
ChatGPT & Gemini say:
Here is a list of streamers that are compatible with JRiver via DLNA/UPnP on the input side and support PSAudio-flavor I2S on the output side to the DAC:
1. **PS Audio PerfectWave DirectStream DAC**
- While primarily a DAC, the DirectStream DAC with the Bridge II or Bridge III can function as a network streamer, supporting DLNA/UPnP input and PSAudio-flavor I2S output.
2. **Wyred 4 Sound MS Music Server**
- This music server supports DLNA/UPnP and can output via I2S, compatible with PSAudio's I2S configuration.
3. **Sonore ultraRendu**
- This versatile network player can support DLNA/UPnP through third-party software configurations (such as JRiver) and can be connected to an I2S-compatible DAC using a suitable I2S interface.
4. **Matrix Audio X-SPDIF 2**
- This digital interface can act as a bridge, taking DLNA/UPnP input from a network streamer or computer and providing I2S output compatible with PSAudio's specifications.
5. **Auralic Aries G2.1**
- The Aries G2.1 is a high-end streamer that supports DLNA/UPnP and can be paired with the Matrix Audio X-SPDIF 2 to provide PSAudio-flavor I2S output.
6. **Lumin U1**
- This network transport supports DLNA/UPnP and can be used with an external I2S interface to connect to PSAudio-compatible DACs.
7. **Pro-Ject Stream Box S2 Ultra**
- This streamer supports DLNA/UPnP and can output via USB, which can then be converted to I2S using an appropriate interface like the Matrix Audio X-SPDIF 2.
Each of these streamers or combinations can provide the DLNA/UPnP input and PSAudio-flavor I2S output you are looking for, covering a range of price points and feature sets.