I have the T-10. Its a good unit, especially if venting forward is the only option. If you can vent to the back, the T-8 should be the winner.
With smart fan turned on, you can adjust the speed and temp the fan runs at... but it is audible. I sit about 8' away. That said, if I am doing other things, the fan isn't disruptive. Just that it is audible. But it keeps my Marantz running cool.
I will likely switch to the rear venting within the year. Had the T-10 since 2018.
I set the unit on top of my converted dresser/stereo stand and sat at my usual 8ftish distance and I could hear it plain as day. I decided to use it for my bedroom as I dont do critical listening there. I also put it there because I got tired of using a wobbly wire shelf to prop up my cassette deck and bluray player above the AVR. I ordered the S8 model for use in the great room.
I set my unit to auto as I dont think smart mode ever shuts off and I close the cabinet doors to keep my hairy cats from climbing all over the electronics. What do you have your trigger temperature set to? Im using 85F.
Correction, I just went up stairs, switched the unit to smart and it never turned on. Maybe it takes 30 plus minutes for the AVR to cool down after use.
One more correction, if the fan setting in on is greater than 3 bars, switch to smart will turn on the fans at my given trigger temperature.