I have recently purchased the NFB-5.2 to drive my Q701s when connected to a PC (Win7/64). To my ears it's a stunning combination and I'm enjoying every minute of using it, but within the gamut of possible choices between the file formats, players, drivers, connections and the DAC, I'm still experimenting to find the sweet spot. Here's what I have found so far:
- Audio file formats: I can hear a difference between 44.1, 48 and 96kHz, but 192kHz doesn't add any value to me. 24 bit sounds smoother than 16, albeit many recordings are ruined by clipping, and that's across the board. 320kps mp3 is as good as FLAC to my ears.
- Player: foobar2000 - mostly because of it's flexibility and ability to pass "pure" signal (however with some recordings this purity is reduced by the need to lower the volume to minimise clipping). But to be honest I haven't done extensive research on players.
- Driver: not much to choose in terms of driver software as usually all one's got is what comes with the motherboard or the soundcard. All you can do is make sure that the installed driver version works well (sometimes this could mean resisting upgrade to the newer one). However there are some driver settings that may have impact on the sound quality: the output port to be used and the default settings. Note that if you use WASAPI plugin these settings may have no impact any more. I'll discuss them in the next point
- Connection: I have tried all 3 of the USB/optical/coax and settled for USB 24bit/96kHz. To me it sounds a bit warmer than coax, with slightly cleaner bass, but I'm not sure if this is really optimal. For example, does this mean that all signals will be upsampled to 24/96 by the PC? In hardware or software? Even if so, this should be better than downsampling if I choose 16/44.1, or even 24/48, right?
- Didn't see any difference between optical and coax (due to my preference for USB I wasn't trying really hard to compare these two).
- Filters: they do have impact, however very subtle. To me #3 sounds most pleasing.
- OPA: to me it only distorts the signal. Why not using equaliser instead?
- High gain setting sounds cleaner and I have an impression that it delivers slightly warmer sound but narrower soundstage, at the same volume levels
I'd be interested in comparing my observations with other users of the NFB5 in similar setups.