As others have said before, it's almost cool with no fan.
The point is that you are talking like you found out some dirty secret about the WiiM Amp Ultra and because of the ingenious move of adding a fan you have been able to mitigate the design error:
There is no design error in the WiiM Amp Ultra. It works and will continue to do so for years to come with no additional fan.
No such thing as a noiseless fan. If you cannot hear it, it really does work for you. Keeps me wondering why you have to shout at us when your fans are all silent.
I haven't seen anything in your posts on this topic indicating that you understood the real problem with the TPA3255 chips. It's not the case temperature. It's the problem of the high energy density because of the very small contact patch these tiny chips have to offer. The key to keeping a TPA3255 based design healthy and happy is to quickly dissipate the heat away from the chip. That's exactly what the heat pipe solution employed by WiiM does. Heat does not simply rise. That's pub-physics, at best. Heat transfer occurs in the direction of decreasing temperature, driven by the local temperature gradient. In other words: Wherever there are cooler temperatures, the heat flux vector will point into that direction, no matter if its upwards, downwards or sideways.
It is and that individual feel is totally irrelevant for if the chip gets toasted or not. It doesn't care for individual perception.
It's totally up to you if you are happy or not with the case temperature of any device. If you don't like it the way it is, you are free to either ditch it or help yourself with cooling fans. That's all fine, you can do whatever you want and additional air flow will never be a disadvantage. Nobody can force you to accept a surface temperature that makes you feel uncomfortable.
But please, don't try to tell anybody that there is a technical problem just because you prefer a different design. Objectively there is no technical problem. No more, no less.
