In the Musician Phoenix DDC Review Sandu Vitalie compared the I2S vs USB on the Musician Aquarius DAC.
II. Musician Phoenix + Musician Aquarius via I2S
The audible difference wasn’t only immediate and apparent as it was with a Singxer SU-6, the difference was actually bigger to my expectancy levels.
On its own, Aquarius is a mighty fine sounding DAC, certainly up there with some of the nicest R-2R DACs I’ve tried to this point, but when locking the signal via I2S from the Phoenix, there was a serious jump in resolution and ultimately, dynamic range.
I would never call the Aquarius as muddy, grainy or soft sounding via USB, but it felt that way when I started my comparisons.
I2S is better than USB in the Aquarius.