Hi does this mean my MP3 file quality became lossless (FLAC?)
No, the source file is a lowly 128 kbps MP3 file. Roon sends a PCM stream to your DAC, and the quality—indicator is low quality—remains unchanged.
No. The lossy mp3 was just decoded and then streamed by Roon using PCM data as it always does. However, the missing information in the mp3 is missing for good and can’t be recreated out of thin air
The Signal Path indicator indicates the quality of that step. So for “This PC” the indicator is indicating that Roon has transferred the source bit perfect, whatever that source may be. In this case, it is showing that it transferred the MP3 source without any further degrading.
@Nut - you should spend a little time reading the articles in the Knowledge Base. I think that all of your questions have already been answered there. For example, this one: