I don't have any with the BTR3 but do with other FiiO gear - currently incredibly happy with my FH7s and my old Q1 MkII was great as well. If you can stretch to the Radsone ES100 I'd grab one in a heartbeat. The app itself is worth it's weight in gold. Do some googling - lots of people waxing lyrical. With that said, I'm sure there's absolutely nothing wrong with the BTR3.
I don't have any with the BTR3 but do with other FiiO gear - currently incredibly happy with my FH7s and my old Q1 MkII was great as well. If you can stretch to the Radsone ES100 I'd grab one in a heartbeat. The app itself is worth it's weight in gold. Do some googling - lots of people waxing lyrical. With that said, I'm sure there's absolutely nothing wrong with the BTR3.