thanks for the feedback.
I used VAC in various setups for different purposes and generally have no problems with it.
With the Flex-5000A, PowerSDR software and the Realtek HD1200 onboard sound I tested all possible parameters and configurations but it did not work without frequent resyncs.
You hardly notice that when listening as it occurs only once or twice per hour or so, but it simply looks bad in the statistics of DRMcalc.
I am just checking SNR from Bolshakovo on 7325 kHz.
With VAC I had 42.5dB some days ago and now via line in cable the SNR is very close to that today. So no problem, I'll stay with the cable for now.