I previously owned a Mimik, I used this with a variety of DACs, including the Numerik. The Numerik was not enough of an upgrade over the Mimik, I doubt its an upgrade over the Genki.
The Benchmark DAC is reportedly a nice DAC, I've only heard it in unfamiliar systems, sounded pretty nice. I think it has higher resolution than the Genki, using it with the Genki as transport should be a nice upgrade.
You should also be aware that digital cables are important, I've tried many, they do make a difference.
One thing to be aware of, most SS DACs may be a touch more analytical than you want. Linn digital is very musical, more akin to tubed DACs than SS. I've owned both the Audio Aero Prima DAC and Audio Logic MX24, both tubed units and closer to the Linn sound than my modded Perp Tech SS unit.