Above an easy to attain level all properly designed DACs are sonically perfect, and it does not really get any better than perfect. So what does an RME ADI-2 DAC buy you over and above a cheaper Topping? Build quality, support and features. Build quality is superb, and so is the support, including software updates (e.g. look at their YouTube videos and their forum, but they also respond properly if you write to them). Features include traditional ones such as tone and balance controls, dynamic loudness, auto reference level, and a range of filters.