Looking at the trinity: Control Point - Media Server - Renderer, we all know that the latter can have a great impact on sound quality. Also, most will agree that the control point can make a difference in that respect.
So how about the Media Server? With all other things being equal, can switching from one Media Server to the other change the sound? Of course I tried myself, and I think I hear some difference between
BubbleUPnP - FEMTOserver - JPLAY FEMTO
BubbleUPnP - JR MC24 (running on another pc than the renderer) - JPLAY FEMTO
But I could be wrong...