The continously advances in semiconductor fabricating process will produce better and better data conversion products, in this case the DACs inside your audio equipments. The differences could be the grading quality of the BB DAC vs. the Ultra Analog DAC, the preceeding digital filter, error correction, dithering or noise shaping stages and no less important the lowpass analog filter stage just before output. So you may have to dig deeper into the design of each piece of equipment to figure out why the discrepancies. Cheers,
