Actually I have tested both the Pioneer and the Marantz dac with the Pioneer being easily better in just about every possible way. Both units are well built with shieleded transformers and linear power supplies but the Marantz uses antiquated (in a bad way, low detail retrieval, rolled off freq response) dac chips while the Pioneer has a pair of ESS 9016 which sound almost good. Not a great fan of ΔΣ dacs but this is not bad for the money. In Europe both units cost about the same, 800€ or so.
Out of the two I would reccomend the Pioneer but on the same price bracket my choice is the Aune S16(which I bought as a secondary dac)