Confused... stream degrading to mp3


I am using SWYH on my PC to stream TIDAL to my Marantz AVR (which has AirPlay). SWYH is set to PCM, TIDAL to FLAC.
I can select ‘Stream to:’ “Marantz”, with the Marantz on. Sound quality is good but not sparkling.
Alternatively, I can access ‘Media Player’ on my AVR (using my Android app) and can see the SWYH stream of TIDAL previously started on my PC. This way, sound quality is significantly better: more depth, more clarity but some evidence of compression twitter.
The AVR reports the stream as PCM the first way, and as mp3 the second way, which supports the presence of compression twitter.
So why is the mp3 stream sounding better (apart from the twitter) than the PCM stream? Am I adding extra processing into the stream by starting it from the PC end, and if so, how can I start it from the AVR end and still get PCM/FLAC?


I just set up the same thing on my marantz. I have to say mine is a close call as to what sounds better. The MP3 stream is pretty good and maybe a tad crisper. Either way I like it with direct monode turned . In PCM the Marantz reports a bitrate of 1536Kbps - the signal is 50% while the MP3 is 100%, is this anything to do with it?
Do you audessey when you stream, what have you found best?
The Marantz remote also lets you choose between the two streams.