Brand new user. I've just put together a Raspberry Pi 3 running the latest download. It works just perfectly with the Matrix X-Sabre DAC either PCM or DSD.
Unfortunately the same is not true of the Resonessence Labs Herus (I have the original version). It creates nasty noises - hums and howls and clicks and stutters. The Herus is a DSD DAC also but it's bus powered from the USB. I have set USB bus power to 1.2a and the red light remained steady throughout, so I don't think it's power. The iPhone is quite capable of powering it from a Lightning to USB adapter for instance.
Anyway a big tick for Rune Audio, a big tick for Matrix X-Sabre compatibility and a thumbs down at this stage for the Resonessence Labs Herus. I will test some more in future.