we have made extended tests here with a roon/PDP3000HV/PA3000HV system and we have found no problems - everything worked as it should.
To better understand your problem I would like to ask the following questions:
1.) Which T+A amplifier or preamplifier model do you use with your PDP3000HV ?
2.) From what I read I assume that you use separate cabling for PCM and DSD between your PDP3000HV and your (pre-)amplifier. Is this correct ?
3.) When you play CD & SACD discs on your PDP3000HV does the switching between PCM and DSD inputs (Input 1 / Input 2) on the amplifier work as it should (i.e. do you get sound output for both disc types) ?
Could you please for a try setup your system for combined DSD+PCM cabling and check if then everything works properly.
Please enter the “System Configuration Menu” of the PDP3000HV and for Output Configuration please choose the setting “PCM+DSD”.
(You can leave all cables in place for this test - no need to remove the DSD cable between DSD-Out of PDP3000HV and IN2 of the Amp).
Details can be found in the user manual on p.50 and in the appendix/wiring diagrams.