Thank you both for your post and thoughts. Here is what someone else had to say about the problem. Thanks PG
Oh dear, where to start?
First of all that APC 1500 is not the problem. I have two of them and they will support voltage in 1 to 5 msec. So forget that as the problem.
With three units having failed then there is something wrong with your installation and or application.
I have pulled the 50 page manual on that unit off line.
First ventilation. It states that the unit must be on top of all other units, and if installed in a closet there has to be forced air extraction.
I need very great detail about your speakers and how they are wired. There may be a serious installation error, which on a forum can only be analyzed with great detail about your installation.
Now those units are very much in the nature of background units.
They contain 16, 50 watt amplifiers. However the max power draw of the unit is 275 watts.
The unit is specified to give 50 watts to 8 ohms, or 70 watts to four ohm loads, only two channels driven. This would give a conversion efficiency of 50%, which would be fairly typical. So you have only 135 audio watts to divide between 16 channels, which is about 8 watts per speaker channel if all are driven. Actually I see looking at the manual, the amps give 1/8 rated power all channels driven, which is 6.25 watts per channel.
It states in the manual, that this unit is not intended for high power application.
If you want to have more than one room playing at more then low background volume, then external amps are required for each channel driven from the preouts. That will get very expensive.
I'm certain you will have another unit blow, if the installation and use is as you have it now.
So to help you further I need to know precise details of the installation, especially wiring details, speaker specifications, speaker numbers and details of any room controls. I need to know how many of the sixteen amp channels are in use.
I also need details of how you have used this unit and intend to use it.