Well I searched maybe half a day through various manufacturers' datasheets, Youtube reviews, forums for Eaton, APC, Liebert, Microdowell, Cyberpower, plus a couple of OEM, and couldn't find any above the mentioned 1600VA that explicitly mentioned quietness or that it turns off the fan when no inverter is running. From APC I know from an employee forum post that SU series was the last to turn off at all, from Eaton I have some experience having used them in a couple dozen customer projects - fan ran always (understandable, double conversion "online" UPS simply needs some cooling). If a quiet 2200/3000VA UPS exists, it may be rare.