I second that, I use my second CCA with analogue out into an old Logitech iPod dock from 2011/2012. If I flick the HDR on it sounds quite boomy and distorted and muddies everything in the process.I have been impressed by the quality of the analogue outlut of the CCA, both the published measurements from Archimago and by listening myself. I had one as input into my old Quad 33 preamp. When I replaced that with an ADI-2 and started using the digital output the sound was cleaner. However I coyld not do any double blind testing. I think it was real but not necessarily to be attributed to the different CCA outputs. My Quad 33 preamp is a really old design after all nand measurements are pretty marginal by modern standards. So the difference was probably due to the preamp vs RME DAC rather than the quality of the CCA.
Anyway, the good news is that the CCA is really good, but the bad news is that it has been discontinued.
By the way, people should realize that the so called high dynamic range setting is just higher output voltage. If the input sensitivity of your preamp is high this setting is to ve avoided in favour of the lower output voltage.
Digital out isn't affected by whether the HDR setting is on or off though