[...] I have not doubt that the listening difference is NOT due to the processing of the RME DAC. I guess JRMC doesn't play well with RME DAC. May be the processing in JRMC of 44.1 is not well calibrated, but I cannot speculate what the root cause is or could be. I have a short and very good (Oehlbach) USB cable (3 x isolated) between my HP NOtebook and my RME DAC, so this can be excluded as a possible cause. [...]
What you mean by calibration? Where should calibration be needed and cablibration of what ?
Oehlbach USB cable? Regarding cables. I am also not buying the cheapest to get also good plugs but Lindy Premium cables are fully sufficient. USB2 cables can be up to 5m long according to standards and even at that length it wouldn't produce any other sound. This is digital transfer of (audio) data. The cable has no influence on the sound.
I'm not clear right now if you understand how the components work end to end when audio is played. Could it be that you are still very much in the analog world? The audio player opens a driver, ideally the RME ASIO driver. Then the only objective is to send the stream of digital data unaltered through the ASIO driver to the device. The ASIO driver is able to communicate with the Windows kernel to be able to send data through USB to the ADI-2 Pro/DAC on the shortest way without having to go through other Windows audio subsystems. The same lossless transfer of (audio-) data you can get e.g. by using Windows drivers like WASAPI, best be used in exclusive mode.
And with this fantastic unit you can check the lossless transfer of audio data yourself in an "end-to-end" fashion from audio player to the DSP of the ADI-2 DAC/Pro. This is the so-called "Bittest". These are small test files (.wav format) which you can download for free (for each sample rate there is one single file) and playback on your player. These files are short, brought to the point. There is no lengthy transfer needed. You can also use the repeat function of your audio player if you want.
The purpose is to check "end to end" whether audio is played back completely lossless. The positive test result is shown on the display of ADI-2 DAC/Pro if all was ok, lossless transfer of (audio) data. This includes the complete digital path from the audio player to the DSP of the ADI-2 DAC/Pro. After that the D/A conversion takes place.
This way you can validate lossless audio transfer "end to end" and more than reliable transfer of digital data is not required. No expensive cable can make this transfer any better. And even the cheapest 5m USB cables, according to standards, needs to be able to transfer data (including audio data) without any error. Otherwise IT would be a mess if you would not be able to make reliable backups of Operating System and user data!
If the Bittest fails different reasons are possible
a) volume not set to 100% on the audio player (the application)
b) not the correct driver chosen, Windows Mixer and audio features in the OS could also change audio data
c) USB transport errors
So if the bit test fails you can (latest) install the RME ASIO driver and keep it open while using the ADI-2 DAC/Pro.
As long as this driver settings Window is open CRC checks are being performed by the RME ASIO driver.
If you have a transport error over USB, you know that the issue is between computer and ADI-2 DAC/Pro.
Maybe faulty cable.
The advantages of ADI-2 DAC and Pro in this regard I have also presented here in this blog article, by the way, can also be read in the manual. https://www.tonstudio-forum.de/blog/ent … ses-en-de/
So there is nothing to "calibrate", no idea what you think, this is a normal transfer of digital data from a player over digital connections, which all work lossless. Any jitter is prevented by SteadyClock FS technology and the final D/A conversion happens on the ADI-2 DAC/Pro with the built-in D/A converter using its own Femto Second Clock. Behind the DAC there are analog amplifier stages. Here you then have additional quality by the four reference levels design in the analog domain together with the feature autoreflevel. Autoreflevel in combination with the four reference levels ensure high SNR and dynamics over a wieder range of volume settings on the ADI-2 DAC/Pro itself.
Using the Slow D/A filter changes nuances of the D/A conversion in the D/A converter chip. I think here you can fine tune a little and I am curious whether you can hear the change and whether you like it. Please report back.
I hope this little overview was informative / interesting for you. Have a nice day and see you back on forum
BR Ramses - UFX+, 12Mic, XTC, ADI-2 Pro FS R BE, RayDAT, X10SRi-F, E5-1650v4, Win10Pro22H2, Cub12Pro