I got around to A/B'ing the E30 and the Ares II. The chain was Windows 10 PC Amazon Music HD app ->Ares II (OS)/E30 (both via USB) ->SA-1 (E30 via RCA and Ares II via XLR) -> Arya. The SA-1 was set to Low Z/low gain and the volume pot was at 2'o clock, which is my comfortable listening level. Amazon Music was set to exclusive mode, which gives direct control of sound to the app by bypassing OS level control. While listening to tracks that emphasize various frequencies, I toggled between E30 and Ares II by using the switch in the front. The process of switching the DAC source on the PC then flipping the switch on the SA-1 was less than a second process. Between the two inputs, there wasn't an obvious volume difference.
Being able to switch the DAC source this quickly, the sound difference between the E30 and Ares II is pretty dramatic and it would be hard to believe that anyone with healthy hearing wouldn't be able to notice. With regard to the sound, the E30 sounds slightly V shaped relative to the Ares II. The bass impact feels more noticeable and the treble is definitely hotter. Furthermore, the E30 sounds more compressed and the sound has a more noticeable "edge" to them.
The Ares II in comparison sounds clearly warmer with mid frequencies being more audible and the treble being tamed without sounding rolled off or losing detail. The sound from Ares II had less of that "edge" heard in the E30 and therefore sounded smoother overall. Because of this smoothing effect, the drum hits feel less punchy. The Ares II also sounds less compressed and more dynamic (I mean dynamic range), which imparts a sense of better spacing. Interestingly, the sound stage didn't seem to change much. Overall, the Ares II sound is warmer, softer, and feels more sophisticated due to better dynamic range.
This was actually a uh,.,,,ear-opening experience. I went into this biased that there will be a negligible difference, thereby confirming my initial impression. But with the benefit of A/B'ing directly and perhaps with a more revealing headphone (my initial impression of was made mostly with Sundara and HD6XX), the difference is dramatic. Keep in mind that by no means the E30 is a bad DAC and I can see E30 performing better than Ares II with certain genres/setups. The differences I noted here are relative to the two DACs.