My experience with Tripplite products in the datacenter environment hasn't been very positive so I don't have any recent first-hand experience with their current product line.

The SmartUPS 1500VA unit is silent except when you lose power. Then you hear a relay click an a very quiet fan. I find it to be inaudible when the stereo is on (which seems to effectively make it a non-issue if you're planning to use it for your audio gear). The 1500VA unit was able to power my system below for a few minutes at near reference levels with the plug pulled out of the wall.

Hope that helps.

Cheers,