I thought the StageDAC can't do 8X oversampling (bottom setting) with 96kHz input. The manual says: "Note: 8-fold oversampling is only possible with digital input signals with sampling frequencies up to 48kHz. 4-fold oversampling is possible with signals up to 96kHz and 2-fold oversampling can be used at all sampling frequencies up to 192kHz." This is at the bottom of the 4th page, in the "Selection of the oversampling factor" section.
I've never tried 96kHz files, but the 8-fold oversampling might explain the fuzz you're experiencing.
You're right. The StageDAC can't be set on the bottom setting while listening to 96khz, and that's what the fuzz was about.
I'm wondering what the best setting is (considering 95+% of my music is 44.1khz, not 96khz).
My guess is to leave computer outputting 44.1, versus 96khz, and having the StageDAC on the bottom oversampling setting.