I did some research on battery backup for my projector, receiver, etc and found that there are a couple things desired in a UPS system that don't come cheap.
1) A pure sine wave output, not square wave or "near" sine.
2) A "double-conversion" or "online" UPS as opposed to "line interactive". This means that the UPS is always feeding the equipment a voltage that is first converted from AC to DC and then back to AC. You are always running off of batteries and protected. This means the voltage is always very stable and doesn't fluctuate to the equipment. There is also no transfer time. Line-interactive UPS units will just feed line voltage as it is to the equipment, and switch to batteries only when power is lost or the change is extreme.
I recently purched a
Tripplite SU2200XL because it had these features. I was also looking for something that had enough of a power rating to handle my receiver which is rated on the back at 1300 Watts. I have my doubts that it really uses near this much at moderate listening levels however.
I think the cheaper UPS units will work fine in most cases. I have used them before for my DVD, TiVo, and PC without issue. I stepped up to this price point because of the wattage rating I needed, and chose the Tripplite over the APC 2200 unit because of the online/double-conversion type.
YMMV, as Jack stated, it is what it is worth to you.
