Sound quality - PC Server and Android

Hi, I have a plex server in my PC with 16 GB ram. I have been running plex for a long time and I decided to try Roon only because of the multi room feature! I have set up roon core in the same pc and plex server is not running, and set up roon in the same server for playback. I have also installed the android version of roon. The functionality works as promised for multi room playback in sync (although the sync drifts away after some time). Now the main setback for me is the the playback quality over the android as well as at the server seems to be lower than original. I have tried many tracks including 320 mp3s, Multi Track Hi res flacs etc but the sound quality is not good. I tried playing the same tracks with plex, there seems to be no problem. Since I am a new user and Roon is much advanced in its functionality, I may have missed some settings or tweaking. Please let me know. Thanks.