You're right however, the DAC can make or break the resulting sound. If the DAC wouldn't be important, we wouldn't have Wolfson, TI Burr Brown or other extremely expensive units. Sony's DAC in this pipeline is like a polish. It doesn't blemish the sound after all that meticulous reconstruction.

On the paper and spectrogram, an SP ATRAC track is not a match for WAV or FLAC, however it has all the ingredients to saturate a high-resolution system and create an enjoyable listening experience. Also it had enough resolution to handle higher-end amateur mastering (in SP mode) and general recording needs (in SP and LP2 mode).

While 44.1KHz is perfect mathematically, 48KHz and 96KHz can create a smoother sound. That needs higher end equipment to hear clearly, but the smoothness is definitely there.