Unfortunately not noiseless in standby ...

Wanted to use the device in the living room to protect the HiFi equipment. The Back-UPS Pro 900 to replace my somewhat dated Back UPS ES 550. Unfortunately, a constant hum in the whole room is clearly visible, even in quiet movie scenes. That made the device therefore practically useless for this purpose.
The current consumption of the Pro 900 is higher than that of the Back UPS Pro 550. The 900 is even warm!

The current consumption is somewhere between 10-20 watts in standby.
(In the Back UPS ES 550 is less than 5 watts. In addition, the ES 550 completely silent in standby)

Here are some details for Pro 900:
The three control knobs are always white illuminated.
The backlight of the LCD display can be switched off, however.
The UPS also has one output for master and slave devices. That is when the master in standby enter (the standby power consumption can be programmed) then the slave output is fully disconnected from the mains. The master / slave function is also deactivated.
A total of eight outputs (low power device sockets) are with overvoltage protection. Four of them are fed during a power outage by the UPS.
The LCD display always shows the battery level and the utilization as a bar chart. In addition, (switchable) can display information such as input voltage, load percentage, remaining duration of Stromversorugung case of power failure, power to the connected loads.
Even the network / DSL connection can be protected against overvoltage.

Supplied with two IEC extensions for the connection of two consumers. An IEC connector to connect the UPS, NOT included. So you have to take the cable from the PC, or buy a cable in addition.

Actually, a great device that is also visually appealing. Unfortunately just not silent. There may be here but also variations from device to device.