The apps are just remote controls, they are not music players.  They have zero effect on sound quality.  

To present the other point of view even while I don’t subscribe to it. At some point in time, the S2 app that works only with compatible hardware will allow the use of HD Audio services that claim to sound better. S1 will not.

That is a difference in the S1 and S2 system capabilities.  The question was about the app.  However, it’s still a useful point to make and potentially of interest to the OP.  We won’t revisit the debate about whether hires gives better sound quality!