Which UPS do you guys recommend for the late 27" iMac ? I already have an Eaton AVR 1250VA but I noticed today that when electricity is down, the iMac will buzz once powered by the UPS. It's like if the iMac power supply is struggling with the load. That made me wonder if it could potentially damage the screen, and transistors over time. I do know that for home consumers, the simulated sine wave UPS is probably more than enough and can handle almost everything. Ideally, I should get a pure sine wave UPS but I'm not sure about the cost. A quick search and APC is asking for $400+ for the 1KVA. Any recommendation is appreciated.