The nice thing about Roon is that it is easy to experiment. I have found that using setting sample rate conversion to Max PCM Rate (Power of 2) with Precise Minimum Phase can provide some subtle improvements on many recordings. I'm using a Denafrips Terminator DAC with Oversampling turned on.
The dynamic headroom adjustment has nothing to do with the rest of your system (amp, speakers, etc). It is intended to allow for DSP processing (including sample rate conversion and filtering) which might increase value of some samples. If you have this set to 0, then any DSP based adjustments which increase the sample value will result in arithmetic clipping of the samples which will reduce sound quality.
If you are not doing any DSP processing, then setting this to 0 is fine. Otherwise, you will probably want to set this to -3db or even a higher negative value, depending on what kind of processing you are doing.
For example, if you want to provide a 6db low bass boost, then you need to use at least -6db dynamic range adjustment to prevent clipping in case your music has any near maximum samples values.
The dynamic headroom adjustment has nothing to do with the rest of your system (amp, speakers, etc). It is intended to allow for DSP processing (including sample rate conversion and filtering) which might increase value of some samples. If you have this set to 0, then any DSP based adjustments which increase the sample value will result in arithmetic clipping of the samples which will reduce sound quality.
If you are not doing any DSP processing, then setting this to 0 is fine. Otherwise, you will probably want to set this to -3db or even a higher negative value, depending on what kind of processing you are doing.
For example, if you want to provide a 6db low bass boost, then you need to use at least -6db dynamic range adjustment to prevent clipping in case your music has any near maximum samples values.