EdW
Senior Member
The case for upsampling in order to create a smooth frequency response up to approaching the Nyquist limit with very little beyond that is unassailable. However the the Mscaler tries to get as close as possible to a true brick wall filter by the use of a near infinite sinc reconstruction similar to the reconstruction recommended by E.T. Whittaker back in 1915 (possibly he did not have DACs in mind ). I don’t see why a decent FIR filter couldn’t do the job just as well as regards audible artefacts with a slighly less sharp brickwall and a lot less computation. There is a case for a sharper filter than most DAC chips provide? Probably not done since the extra DSP adds more opportunities for contamination of the audio and the analog CMOS processes used for DACs aren’t particularly fine geometry so the resultant DSP could use significant die area.