I've found there to be a pattern in what happens to the sound between the dichotomy of options WAV/FLAC, AES/SPDIF, USB/NAS. There is a change in tonality/presentation as you go from WAV to FLAC for example. I notice similarities in the kind of changes that take placed between the other options as well. I'd group them as this: Group 1: (WAV, NAS, AES, Jitterbug used on PC USB output to DAC) + Group 2: (FLAC [compressed], USB drives, SPDIF, No Jitterbug used on computer)
Group 1:
This group sounds more open, smoother, darker and duller sounding, and relaxed but can feel lacking in detail (especially initially or when going back and forth between their counterparts) and lacking in punch, but has more body.
Group 2:
More exciting, narrower soundstage, image feels more locked in, upfront and exciting, a sense of increased dynamics and more punch. There is no smoothness going on here as it applies to both vocals and instruments.
In quick testing, Group 2 always sounds more detailed and exciting. Group 1 on the other hand can seem less detailed, less dynamic and diffused. This feeling does go away after long and continuous listening. I feel it takes a lot longer for the brain to calm down and adjust and buy-in to the sound of Group 1. Going to Group 2 and getting acclimated on the other hand takes little time as it's exciting.
However, when I listen exclusively to one group without any switching and forget about fidelity or SQ, I feel I can listen longer and with less fatigue to items on Group 1. It flows better and is easier on my ears. The opposite tends to happen with Group 2. It starts off great, but overtime can feel fatiguing. Another side note about dynamic range. With compressed and popular music, I think Group 1 can seem less punchy. However, when you play material with a large dynamic range, I find that I can hear both the music get loud (with ease) but also get very quiet. With Group 2, it always feels more lively, but you never feel it quieten down as much.
I'm not stating this as a universal truth. It's just been my experience over the years. Perhaps I've been conditioned this way due to pre-existing biases, my current ears, or the content I'm listening to and the speakers/headphones and room I have.
If Group 2 is the more accurate group, I can totally understand that as it always sounds locked in and exciting from the start. Perhaps, it's my equipment/ears that for some reason doesn't let me listen to that configuration for a long time. I can also understand Group 1 being better as it can start off weak, but it sounds relaxed and fatigue free in the long run.
