Can you hear bit rate?

@panzrwagn 

disagree that the early Philips '14-bit' CD players sounded better

I did not say they sounded good, just better than their contemporaneous competition!

Philips realised that they simply could not trim a resistor array precisely enough for those two least significant bits to be monotonic.

On the positive side, they used quadruple oversampling from the get-go, eliminating the so-called brick-wall filter with its nasty phase artifacts.

Anthony Cordesman wrote in Audio in 1986 "(French magazine) Son tested nine different Compact Disc players and found significantly different performance with regard to separation, distortion, and phase, pulse and square-wave response. The machines with the worst measurements, all of which use the 16-bit process developed by Sony, had well over 80° of phase shift, poor 1-kHz square wave performance and a considerable amount of ringing"

So, apologies, I meant to ask: Can you hear differences as the sample rate or bit depth changes?  

I was just about to throw darts at it, but now it makes sense. I think it’s indeed possible to hear the difference in bit depth—especially with more complex passages like symphonic orchestras—because of the much higher dynamic range (around 146 dB for 24-bit compared to 98 dB for 16-bit).

As for sampling rate, yes, we can often perceive improved sound quality—typically a smoother top end or more natural transients—when we upsample or oversample the signal. This is mainly because upsampling shifts artifacts such as phase distortion and pre/post-ringing to higher frequencies, beyond the audible range.  My Harmony Micro DAC offers both OS and NOS modes, and I did notice a slightly smoother, airier top end in OS mode, though with a bit of loss in detail. Personally, I prefer NOS mode.

As is known, upsampling can cause clipping, so I do reduce the overall signal gain a little.  Roon converts everything to 64 bits before this so I can do this without further loss. 

What you did (reducing the gain) is perfectly fine, but I just want to clarify that upsampling itself does not cause clipping. The 64-bit floating-point processing within Roon’s DSP engine, where upsampling occurs, provides virtually unlimited headroom, making clipping literally impossible at that stage. Clipping can only occur when Roon converts the signal back to fixed-point formats such as 16-bit or 24-bit PCM, as supported by your DAC. You can either apply a limiter to prevent this from happening or, as you did, reduce the gain to ensure that the converted signal never exceeds 0 dBFS.

@lanx0003  - Benchmark Media put a good white paper together on this.  I believe this is the right article.  Upsampling can cause clipping, I’v heard it happen, but it depends on HOW upsampling interpolation is done. 

Linear interpolation won't do it, but more advanced curve fitting algorithms CAN cause clipping because the curve past what used to be maximum output value goes past it before returning.  The other place it can happen isn’t really clipping, but if you use EQ.  For instance, if you significantly boost the bass, you may need to adjust the overall levels to make sure that extra bass doesn’t clip. 

Op, thx for the article and I enjoy reading through and understand it.  Basically, what it says is that upsampling will identify true peaks (intersample 'over') of the original analoug waveform that might exceed 0 dBFS AND cause clipping IF there is not enough headroom.  In the case of Roon, there is almost unlimited headway and it won't clip until the output stage to your DAC.

Second, it is obvious overly EQ bass (or other part of spectrum) will cause clip simply because you overly boost it