In that case, then, the R3Pro is really just functioning as a file browser/server, no? All the decoding and amplification is happening in the HipDAC. Theoretically, at least, pretty much any DAP (or phone or computer, etc) would sound equally good. I'm not arguing that it isn't an excellent combination - just pointing out that whenever you use an external DAC, the source device has little if any effect on the sound (aside from perhaps any very subtle effects of bitstream jitter or stability). The DAC and its amplifier determine the sound.
Unless the HipDAC has an analog input to function as an amplifier only, which I'm pretty sure it doesn't. ANyhow, I'm glad that combination is working well for you. I've considered the HipDAC myself for using with my phone or laptop, but probably wouldn't with my R3Pro, since that already contains an amp and DAC, and I don't need one more thing to carry around.
Just a thought - I know many people prefer to use external DACs with their DAPs - I wonder if anybody makes a "DAC-less" DAP for just that usage scenario. I'm imagining it as including display, storage, maybe WiFi, pretty much all the usual features, except that it only outputs digital. No DAC, no amp. It could be sold for probably half the price of a full player, and then the user can use the DAC/amp of their own choice.
