I heard a T2 at a local hifi store and thought it sounded fantastic. It was in a completely different system from mine, so no way of comparing apples to apples how it compares to my TEAC NT-505. What I can say is that at less than half the price, the NT-505 sounds fantastic compared to the Bluesound Node 2/Auralic Vega combination that it replaced.
As far as the app goes, I'm an Android user, and I thought the app sucked. The TEAC app is basically a re-badged version of the Lumin app. The Lumin app works with the TEAC also, and that's what I was using. It would take minutes every time I started the app to "find" the NT-505, which was really frustrating. I replaced it with BubbleUPnP, which cost $5 for the version with no ads and works wonderfully.