I have the same problem and it has no real cure.
I have 4 x Chihiros B45 and 2 x AII601 Max. I'm not even intending to update to the newest firmware, because the problem is not there, which was even proven above.
The problem is mainly in how the motherboard inside the commander is connected with the plastic cover. Just by touching the walls it resonates and makes things much worse. I bought additional Commander 1 to open it and check what makes this noise. There are at least two components, but one is most noisy and goes quieter if touched by wooden toothpick. Funny thing, but if I take out the motherboard from the plastic cover the high pitched sound suddenly disappears and is almost impossible to hear. When I place it back the sound is strengthened by the plastic cover and it's very loud again.
With AII601 it's even worse and it's soundless only on 0% or on 125%. No, not even a 100% makes it go quiet on the original commander. But if I change it to the Commander 1 it is once again soundless on 0% and 100%. So it's solely the Commander unit issue.
Because I also have Chihiros WRGB2 Pro 30, which was my very first lamp, a very expensive one, but it was really great for a brackish aquarium too. It was and still is absolutely soundless. But B series and especially A series are very loud ones. And the sound us unbearable.
I have a large amount of plants that need artificial light which I want to change. The more simple and less expensive Chihiros lamps seemed like a very good option to provide my plants slowly intensifying and dimming light. That proved to be a very useful feature for good growth. The price and light efficiency as well as easy to use App with possibility to set any kind of light are a great combination. But why none of B or A series controllers can be as soundless as Chihiros WRGB2 Pro? Or even other companies like Sinkor?
Also I will NOT be updating the firmware, because after updating it in my WRGB2 Pro 30 I am no longer able to control it with WiFi Hub. That issue is not just my own problem. It is unsolvable. I can only turn it on once and do nothing else after that through Wifi Hub. The firmware is the newest and that became the problem. I would need to buy a new commander and not update it to be once again able to control my lamp. On the original firmware, the new lamps are still possible to be controlled through WiFi Hub. The latest update just incapacitated the WiFi Hub control and that should never happen. So unfortunately, the solution for cheaper lamps controllers are not as good as for the one the more expensive ones. It is a pity, because the lamps themselves are great and I was hoping to change at least 12 different size lamps into Chihiros series A or B, but with so much noise around it would be unbearable to live with them. I also don't want opening all commanders and having them naked to make them soundless. I had opened the the existing controllers, saving the extra one untouched if any lamp had any issue to have one for a guarantee return if needed. But no one should break their stuff to make it work normally.
I hope this message stays, because this is what other Chihiros users should know. There are many ways to inform others about this issue. The best way to make it go away is to fix it, Chihiros... You have great lamps, but you saved a bit too much on the controllers for the simpler versions.
