The impulse response is the measure how high the amplitude of peak and the dispersion. If all energy is concentrated at the peak, less dispersion (ringing) occurred. This translates to better transient response and less distortion. DSD is better because it doesn't use over sampling digital filter, so it doesn't suffer from this issue. If we bypass the over sampling digital filter in PCM we can have a good impulse response but drawback is there's going to have noise, especially 44.1k which very near to the 20k audio band. DSD sampling at least 2.82MHz and above, so at that high frequency it is easy to filter with a gentle low pass filter. To avoid PCM going to the over sampling digital filter some convert 44.1k to DSD on the fly inside the PC. Many reported it sound more 'analog' then playing back PCM directly. PS Audio DirectStream DAC is one example. Holo Spring has two option, play in NOS mode (no over sampling digital filter but higher noise ) or use the internal hardware to convert PCM to DSD256 on the fly. But trust me, I still prefer to run in NOS mode, even in 44.1k, everything sound so natural and real. You have to listen for yourself then only you know how good it is!