Voltage Regulators

Sounds similar to a Sola line-regulation transformer with a tertiary buck/boost winding. I have one in my shop, which I use for line isolation/saftey purposes only. The limited power available would likely constrain current-transients, but that may be alright for source components only. A number of the original audio-grade power-conditioners employed line regulation; dunno if that technique is still in-vogue, excepting such devices as PS Audio, but they do far more than that of course. I wouldn't expect the device to improve your audio, but the only way to know for sure is to try it. Bear in mind that most audio component's power supplys are already regulated though. It also might offer some protection from AC line-transients, although there are more effective methods of accomplishing that.

A voltage Regulator is just what is says it is. It maintains a constant voltage given a range of input voltages. In this case it specifies 80-130 VAC. The question becomes - what is this solving for your system? I am not sure about the claim on the web page of "true sine wave form output" means. Also with something like this there is an issue of current limiting. For source devices it might not be an issue. Also many pieces of equipment contribute RMI back into the power cables. So again what problem is device solving for audio components? Its not clear from the web page or buy its intended function as a voltage regulator.

I have always wondered about using one of these with hifi gear but have never looked into it. I have in the past used commercial regulators with test equipment like scopes and thermocouples in a R&D facility and assumed that they helped maintain calibration of the instruments. A cool box for $50.00 sounds good to me though there must be a catch as I have never seen one used in a hifi system even ones owned by electrical engineers.