Scrith
500+ Head-Fier
No, based on my experience, a power conditioner won't make a significant difference (unless your power is much worse than average, I suppose). But they seem to improve things a little bit.
By the way, in my experience, using an uninterruptible power supply (UPS) is the absolute WORST thing you can do to your audio hardware. I've personally compared APC UPS devices to PS Audio power conditioners (UO and P500) and found that they noticeably reduce the quality of the sound. I'm guessing they'd fare even worse against the newer PS Audio gear (e.g. Duet and Premier) because those sound better than the UO and P500 (again, based on my own tests).
By the way, in my experience, using an uninterruptible power supply (UPS) is the absolute WORST thing you can do to your audio hardware. I've personally compared APC UPS devices to PS Audio power conditioners (UO and P500) and found that they noticeably reduce the quality of the sound. I'm guessing they'd fare even worse against the newer PS Audio gear (e.g. Duet and Premier) because those sound better than the UO and P500 (again, based on my own tests).