Dear Marcin and Josef,
The latest Roon 1.5 version now supports streaming to LINN DS products. It seems LINN had to get some firmware updated to make this happen.
Since Jplay already supports Openhome, is there a possibility that Jplay Streamer can operate like firmware upgraded LINN devices to be directly discoverable by Roon Core? (I tried, it didn't work on my system.)