iFi nano iOne is a usb, Bluetooth and coaxial/or optical input dac. Perfect to connect to a stereo or higher end headphone amp. Can decode DSD256 via usb and the bluetooth input uses AAC for great sounding iPhone connection, as well as apt-x for android.
rca ouputs to stereo. iFi's Active Noise Cancellation tech is built in, to filter and provide a clean power source from usb.