Ok, so I received my Topping E30ii and tried it in my system yesterday.
I used a Marantz CD63 KI Signature as a transport, and used a pair of KEF LS50 Wireless MkII .
I A/B/C'ed the 3 DACs:
- the Marantz's
- the Topping E30ii
- the KEF LS50's
I played Buena Vista Social Club, and Johnny Cash's American Recordings vol.6 as reference CDs.
This is a purely subjective review, of course, FWIW.
My spouse and I found it hard to distinguish between the Topping and the KEF's internal DAC. I may have perceived a bit more detail & dynamics with the Topping, but that could just be some psychoacoustic artifact.
Anyway, the fact that the €150 Topping is equally as good (to these ears) as the DAC inside the 2500€ KEF LS50s speaks volumes.
The Marantz' DAC, while still perfectly adequate for me, sounded maybe slightly muffled compared to both the E30ii and the LS50 DAC. Hardly surprising, as it dates back to the mid-90s.
Concerning the aformentioned "treble harshness" of the E30ii: I heard none of this. I heard no difference in treble content between all 3 DACs.