What kind of stepped attenuator is used in the Tisbury preamp? I personally think that a garden variety 23-24 step attenuators are too coarse and I often find myself in a situation where my desired setting is between two steps which is mildly infuriating. The Schiit at least gives you 64 steps (1 dB each) and this is a huge advantage in my book.
Also with the Schiit unit you can switch between passive and active if you have problems with impedance mismatch.