It seems that the XMOS and MCU updates for my SN: 11xxxxx Tone2 Pro was successful. I remeasured the response of the filters with v1.0 firmware (before upgrading, as a baseline). As you can see here, the response of my unit was identical for all filter settings:
I’ve separated the lines on the plot. If I did not, you would only see a single line because there was absolutely no difference in response!
After updating XMOS and MCU firmware, here’s the new response of these filters:
I’m not sure how audible these differences are (note the very small scale), but the filter selection knob is now clearly working. Yay.
As promised, the new firmware addresses phase as well. Step response with firmware v1.0 was inverted:
Step response with firmware v1.2 looks correct:
Noise and distortion has improved with the firmware updates as well. Here’s distortion and noise under v1.0 firmware:
With v1.2 firmware, we no longer have that “Loch Ness” spike in 2nd order distortion at around 14 kHz.
So, congrats Khadas team. The v1.2 firmware seems better all around!
Note: I did have problems with my Tone2 Pro intermittently flipping to mono under v1.0. I understand that’s been fixed with v1.2, but I won’t know until I go for a few months without it happening again. Fingers crossed. 
Edit: Distortion and noise at 352.8 and 384 kHz with the v1.0 firmware was pretty terrible. I don’t have a lot of content at that sampling rate, but this distortion was audible.
I’m pleased to report that this too has been sorted with firmware v1.2:
This is quite good news.
If you’d like to explore my REW files, you may download them from here.
