No problem. Thanks again for trying to explain. I understood the fundamentals of a balanced connection/signal. It was just the way you mentioned how dCS implements the output circuit for balanced and unbalanced I wanted to understand better. Was trying to get a better idea of how the dCS implementation of two separate circuits is superior.
All I can say is that different designs have been used for the RCA or balanced analogue outputs. Both were regarded as state of the art at the time of release , the former using OP amps and the latter being based on discrete components. Of course the Apex upgrade has involved a change to these outputs but I am unaware of exactly what has transpired. I do know that the result is superb for ( in my case) the balanced output though exactly which part of the upgrade is responsible for which sonic improvement is not known. In fact I donāt need to know as all I have to do is enjoy.
I have several sources connected to my integrated amp, and I prefer them to be similar output. Otherwise I need to remember to turn the volume down before changing sources, or else get blasted out of my seat sometimes.
My DAC is the Lina, not Bartok, but it probably works similar with respect to volume control.
In my case all of my other sources are 2V single ended, and I have found I prefer the sound quality of my amp with single ended inputs, even though Iāve tried some very well regarded XLR interconnects.
So itās easy for me to set my Lina at 2V fixed output and enjoy the music.
I suspect the choice of single ended or balanced depends on the choice of source and pre-amp. Happily I like my Lina with single ended output. You certainly might prefer your preamp with balanced input, and trying it is the best way to satisfy your curiosity.
If you donāt have multiple sources, then the level doesnāt really matter, except for your judgement of the best sound quality (assuming the preamp can handle the voltage), and the C53 XLRs can.
Your stated ways to go:
A. Same as what I am doing successfully. I have 1.5m cable length. Apparently longer cables are higher risk for RFI/EMI. How long is too long? Probably depends on your cable shielding and your environment.
B. This seems worth trying, especially in light of Peteās assertion that discrete components might be used for the dCS balanced circuits. I have discovered that the variable output feature of my Lina must be enabled manually on the front panel. After it is enabled, the volume can be changed in Mosaic. The same might be true for your Bartok. On my Lina, I opened the menu, then paged to the gear (Device Settings), then selected Volume Lock to unlock it. The DAC instructed me to restart the DAC to make the volume control effective. Now I have the volume slider bar in Mosaic. This where you can set the volume to -3.5 dB (or manually on the face of the device). One nice thing about enabling the volume control is remote access to the phase control. Touching the musical notes to the left of the volume slider toggles the phase between normal and inverted. In my experience, some devices and recordings sound better with inverted phase. So it is nice to have that control handy. I will keep my volume at 2V full output (0.0 dB) since that is what matches my other inputs.
C. I do not recommend this, but your experience could be good. I have all my amp processing turned off. My amp has pretty meters, but I have them turned off. Likewise, tone controls and loudness are disabled. This is because (for my amp and my experience) these processes degrade overall sound quality.
Good luck and happy listening with your Bartok!
Thanks Pete again for helping me through the first few days of ownership! I have to say being new here that this has been a very welcoming community.
Best