This is the 2nd of these Units I have. The first one is in the white case, and has been functioning for me flawlessly for 6 years. Prior to that, it was used in a gold plating application to regulate the voltage to the plating elements--- too high a voltage, you use too much gold losing $$-- to low a voltage-- you get crappy plating.about 6 years ago I got a flat screen, and now it's used to protect that.
1.) No hum at all
2.) give it space to cool by convection. There is no fan, and will generate heat without a load on it.
3.) yes it clicks when your voltage changes, but that is good! You can see it adjusting to compensate for a high or low voltage condition.
Invaluable in--- Ice Storms, Thunderstorms, heat waves, numb nuts running into a utility pole on your grid-circuit, etc
4.) It is not a UPS - If the power goes out, you have no power (duh)
5.) It provides surge protection as well as the voltage regulation
6.) It's large and heavy built like a tank
An old CRT bit the dust last week, and I had no hesitation buying another one to use there. It also filters out electrical line noise, which acts like a hacksaw on some electronics.
The New unit iappears just as solid as the old one.
Know what you are buying, and if this is what you want, you will be happy, happy

This unit feels high quality and it definitely does SOMETHING but has downsides. I installed this unit to protect my entertainment center from my 6kw generator. When my refrigerator turned on this unit would briefly show the low voltage light. When the refrigerator turned off it would briefly show the high voltage light. Makes sense. BUT, when correcting the voltage the unit makes a loud click and my sony led tv flickers. The tv flickering tells me it's certainly not a seamless voltage correction. I hope it's not doing damage but have not measured it yet. As others have said you can hear this unit operate. When it corrects the voltage the loud click or SNAP is loud enough to scare my dog. It also can be heard humming even on clean power. Is it loud? No. Can I hear it when the room is quiet from 10ft away? You bet.

I really like this unit, which protects a Brother monochrome home laser printer, It is silent until I print a page, at which time there is a low clicking sound as it springs into action to boost the voltage going to the printer. Otherwise the printer would experience a five or six volt power drop.

The printer is the only item connected to this device. Accordingly, the power drop impacts the rest of the circuit. However, I use a CyberPower UPS (with true sine wave output) to protect my computer and related gear. A five or six volt circuit drop is not sufficient to cause the UPS to switch into battery boost mode, but it does protect the computer from a really bad power surge or sage.

Thunderstorm season is coming here in Washington DC, so this hardware combo of line conditioner forn the laser printer and UPS for the computer and related gear gives me great peace of mind.

The actual continuous current usage is 12amps/1500w. The non-continuous correct is 15amps/1800w. The info they give while not a lie is misleading. See attached photo from the a/c power cord. This is the reason for the 4 stars - thus far.
On reading reviews about hum, their customer service dept said if it hums send it back.There is no internal fan. The unit is silent.
On reading about the switching clicks - the sound is very quick and not even a snap. Unless it is in a recording studio with live mics I can't see why anyone should be concerned.
On reading that the unit should be replaced annually because the unit will continue to run after the "sacrificial parts" have burned out (presumably in a large surge), the service dept says it will no longer run.
I just got it 2/27/17, so can't state about its long-term usage. Unless you see an update, it has continued to be of good service.

This Tripp Lite LC1200 line conditioner seems to be working as advertised. I use mine to protect my TV/entertainment center. During those occasional voltage sags, I would hear the clicking sounds when the internal relays activate to boost the voltage.

These line conditioners are a big improvement over the common plug-in surge suppressors. Surge suppressors are ineffective to protect against brownouts and voltage sags, nor can surge suppressors deal with extended voltage surges. The line conditioner can do all that. However, the price you pay for this broad protection is the high standby power consumption. There is a heavy internal transformer in the line conditioner and it consumes roughly 20 watts just sitting there even when all the appliances are turned off.

The massive transformer also gives an audible hum that some people may hear. The small hum gets drowned out as soon as I turn on the TV. Only when I sit right next to it in a totally silent room do I hear the hum.