Greetings from USA! Thomann recently sent the EQ Mastering Edition to my porch in record time. I have completed two mixdown sessions with the Elysia on the master bus.
The box is more flexible that at first apparent. As expected, it can add body and subtract irritants relatively well. Even at the full turn of a knob, the filters do not ring harmonics in a way that is noticeable...although most of my adjustments have been under 1dB and the largest at 2.5dB.
The EQ is not completely transparent. There is indeed a character to the unit, but it is subtle, so I would not characterize the sound as surgically clean. Passing audio through the Elysia and making even the smallest adjustment ever-so-slightly fattens the sound with harmonics in a fashion that increases the apparent volume. The result is quite musical and I have no complaints.
The harmonic coils at the bottom and top are a bonus and they can be addictive once engaged. The tendency is to make their effect too strong at first and a night's sleep quickly makes the previous day's adjustment rather obvious. Fresh ears suggest just a touch of this effect is all that is needed to add a slight sheen to a mix. The effect will blur microscopic detail, so the feature would not likely be used on acoustic genre like classical and acoustic jazz (the 4-band EQ can still assist these genre without the coils engaged). But the coil feature is fantastic on rock and pop. It definitely adds apparent fidelity for playback on mid-fi devices like inexpensive ear monitors and bluetooth speakers.
This is not an invisible surgical tool like a Maselec (super expensive!), but the Elysia can add perspective and sheen to most reasonably-mixed music. While I can imagine doing some mixes without the Elysia Mastering EQ, I suspect it will be strapped in the master bus for the majority of my work.