Thats not what I asked or am I misguided
If both rebook and DSD are converted to DXD via HQP why wouldn't the files of the same song sound the same
And what happened to last year's mantra that listening "native" sounds the best
A simple question with a not so simple answer. I will have a go at it and try keeping it readable.
First a few definitions, source Wikipedia.
1) An
analog-to-digital converter (ADC, A/D, A–D, or A-to-D) is a system that converts an analog signal, such as a sound picked up by a microphone or light entering a digital camera, into a digital signal. The
difference between an input value and its quantized value (such as round-off error) is referred to as
quantization error.
A device or algorithmic function that performs quantization is called a quantizer. An analog-to-digital converter is an example of a quantizer.
2) The conversion involves
quantization of the input, so it necessarily
introduces a small amount of error. Furthermore, instead of continuously performing the conversion, an ADC does the conversion periodically, sampling the input. The result is a sequence of digital values that have been converted from a continuous-time and continuous-amplitude analog signal to a discrete-time and discrete-amplitude digital signal.
3)
An ADC is defined by its bandwidth and its signal-to-noise ratio. The bandwidth of an ADC is characterized primarily by its sampling rate. The dynamic range of an ADC is influenced by many factors, including the resolution, linearity and accuracy (how well the quantization levels match the true analog signal), aliasing and jitter.
5) The resolution of the converter indicates the number of discrete values it can produce over the range of analog values.
The resolution determines the magnitude of the quantization error and therefore determines the maximum possible average signal to noise ratio for an ideal ADC without the use of oversampling.
6) In ADCs, performance can usually be improved using
dither. This is a very small amount of
random noise (white noise), which is
added to the input before conversion. It extends the effective range of signals that the ADC can convert,
at the expense of a slight increase in noise – effectively the quantization error is diffused across a series of noise values which is far less objectionable than a hard cutoff. An audio signal of very low level (with respect to the bit depth of the ADC)
sampled without dither sounds extremely distorted and unpleasant. Without dither the low level may cause the least significant bit to "stick" at 0 or 1.
With dithering, the true level of the audio may be calculated by averaging the actual quantized sample with a series of other samples [the dither] that are recorded over time.
7) As per the Nyquist–Shannon sampling theorem, a
digital-to-analogue converter (DAC) can reconstruct the original signal from the sampled data provided that its bandwidth meets certain requirements (e.g., a baseband signal with bandwidth less than the Nyquist frequency).
Digital sampling introduces quantization error that manifests as low-level noise added to the reconstructed signal.
8)
Noise shaping works by putting the
quantization error in a feedback loop. Any feedback loop functions as a
filter, so by creating a feedback loop for the error itself,
the error can be filtered as desired.
Going from these definitions you can see that error's are introduced, some unavoidable like
quantization error, some deliberate like
dither. This happens
twice, in different forms, on both the
A to D and
D to A conversion. These
sum to a total X amount of error or deviation from the original source.
You could see why increasing bandwidth and signal-to-noise ratio on the A to D side can result in lower error rates / noise and therefor deviation from the original analogue master independently on what you do on the D to A side.
HQplayer has an array of options to deal with errors and noise up to the Ultimate
for me which is upsampling to DSD which is where digital and analogue meet in the middle by using the same waveform.
And that service includes determining the best options for YOUR setup. So, in practice, you won't have to deal with the configurations at all. All you'll see is Roon, and everything else will be taken of, out of sight. 
