Plantronics USB Headset Stutters After Upgrading to 10.12.4

I've got a Plantronics USB Headset (a basic headset, http://www.plantronics.com/us/product/audio-478). I've used it on this and previous MacBooks for about three years with no problems. Today, after updating to 10.12.4, it started stuttering. It's bad enough I can't understand anything through it.

I am on an early 2015 MacBook Pro Retina, 13".

- Input and Output from the built-in audio is fine

- Output from a USB connected headphone amp is fine

- Other USB devices, like my keyboard, are fine

- I have two of these headsets, both exhibit the stuttering but both worked fine before the upgrade.

- I have reset the SMC and PRAM.

- I have changed which USB port it is plugged into including unplugging all other devices

I'm not sure what else to try at this point. Any help would be greatly appreciated.