There are some characteristics of tubes that cannot be simulated or EQ'd. First, tube distortion tends to be more even order harmonics which means the added distortions are incremented in octaves so that it gives sound a more full/richer tone. Next, tubes measure consistently across power output whereas solid state tends to be optimal at full power. There are other differences like feedback and clipping, but these are the main points. However, if purity is your goal, then putting any amplification to the H2 or even Dave goes against that philosophy (and Chord's). In fact I think most Dave owners sell off their expensive amplifiers.