No embarrassment necessary Max - I wasn't suggesting you use JMRI. Just that it's about 1,000% better than CVs in Hex! 
No need to learn it when there's a nice OEM alternative! The Lokprogrammer screens are very nice. At first glance I think the 20 and 40 kHz settings might be for frequency sent to the motor under DC operation. I think the thing you need to change is the "Adaptive regulation frequency" - checked or un-checked. And possibly try adjusting the "Back EMF sampling period" slider underneath. But I think it's the former. Checking and un-checking should change between variable frequency PWM under Back EMF that will drop into audible range at starting and slow speeds, vs. running at a fixed PWM frequency above audible.
But like I said, I am definitely not 100% sure of this so hopefully Dave Heap can supply the correct answer. I would be grateful to hear his response!
EDIT: OK I just listened to the motor buzz. That sounds like a loco with no decoder! I don't hear any kind of variable Back EMF or PWM control sounds happening there. None of my DCC decoders of all brands sound like that under any setting. But all my DC only locos sound exactly like that before I put the decoders in.
WEIRD. Now I am quite confused, sorry. 
Pete
