The Topping isn't bad with the HE-6, I was using one prior to getting my Taurus MKII. In retrospect, with the benefit of hearing the 6 from the Taurus (which I think is probably still a ways off how good the 6 could sound on the right speaker amps), I would say that the Topping is sufficient to bring the bass, slam and dynamics out of the 6, however the imaging and soundstage and refinement/micro detail will not be approaching their potential. It's a decent stop-gap for the price.
Why do you say that? I have tried several good speaker amps, and the Taurus is better. I would be really surprised to find anything significantly better than the Taurus.