Theo, there seems to exist an old wives' tale that class D amp suffer from some arcane form of pernicious system dependencies... The answer is both yes and no....
In olden days, a number of entry level class D amps suffered of relatively high amounts of the shrillies, as they seemed to leak persistent hash from everywhere... They did need some kindly filtering somewhere in the system, lest they could drive you batty. Furthermore, some class D amps had relatively low input impedance, limiting successful coupling to preamplifiers.
With newer generation power conversion modules, such as NCore technology for example, the above is definitely no longer a problem. The Veritas in particular, have an input impedance of 90K Ohms... You will have a hard time finding a preamp that is not compatible. On the output side, unless you try to drive absurdly sensitive speakers, the 1K damping factor will serve you well.
Merrill Veritas are extremely sweet sounding, and do not appear to be feeding perceivable hash into the AC line. having said that, while the amps are shipped with fine power cords, you may want to experiment with PC alternatives. I have experienced excellent results with Aural Symphonics on Veritas, as explained in my scribbling. In older days, with ICEpower class D amps like Rowland M312, Bel Canto Ref1000M Mk.2, and REF500M, I had the opportunity of testing with the Shunyata Z-tron series, which controlled treble intermodulation artifacts to a superior degree... I have it from reliable sources that the Cardas Clear family may also be consistent with this behavior.
Best, Guido