Update: I opened a case with Lenovo support and was told to run full unattended boot level diagnostics, which includes CPU stress testing. Everything passed. I was then told to unplug the external power supply and press the power button for 60 seconds. I was told this would force a static discharge of the internal capacitors in the PC.
After doing this, I started Windows 11, Cantabile Performer and Ivory 3. Problem gone!
CPU-Z is now showing a fairly consistent CPU speed near the max specs and there are no dropouts or crackling when I play using Ivory 3. Previously the speed was fluctuating all over the place when Cantabile was loaded.
I’ve spent the past week working with Process Lasso and Throttlestop and wasn’t able to solve this. I’ve never heard of this procedure before and haven’t found anything on the web about static discharge solving audio dropout problems. I’m crossing my fingers that this fix lasts but right now all good.
Shout out to Brad. He’s been very responsive in trying to help me with this!
I’ve set my power management to high performance with min/max processor and cpu parking min all set to 100% per Brad’s recommendation. I’m going to keep those setting for now even though I imagine I’m getting more fan noise than I would without these overrides. At some future point, if everything’s working and I’m feeling bold, I’ll retry the default balanced plan. Right now, I’m just happy to have good sound back!