APC H-15 does the job nicely but I get a thump too. The tump comes from the 990 not from powering it on a off. The H-15 will sense a problem and turn everything off for a few minutes until it senses stable voltage. It won't turn the equipment back on just supply power back to it for you to start it up again. I can count at least 4 times it has saved my setup. After one storm I had the only HT left between me and my two closest neighbors. I got 2 from Audioholics a while back for < $100 each. It protects my stuff from the lightning storms we get down here. I can't imagine not having them.