I've had a TrippLite and a ZeroSurge and they both negatively affected the sound. I thought I could do it on the cheap and was wrong. I've been using the Audioquest Niagara 1200 for years and the sound is cleaner with no leading edge etch and no restrictions in soundstage or dynamics.
Although passive in design (no transformers) it still "conditions" the sound, if you want to get technical, in cleaning out the grunge and I believe, scrubs DC offset noise if present in your system, and that's where a large share of the noise can come from.
It has non sacrificial surge protection that immediately clamps down on surges, and keeps on keeping on. Garth Powell left Furman to go work for Audioquest so there's some decent engineering behind it.
The only downside is that the price has gone way up. I paid $1,000 and now it goes for $1500. They have other models priced above and below it that supposedly do the same, or similar things but you'll have to dig deeper to find out.
All the best,
Nonoise