Many of the garden variety UPS inverters output a square wave, or close to it. It is rich in odd order harmonic distortion, primarily 3rd, 5th and 7th. Actually, this type waveform will provide a more efficient power transformation in rectifier fed equipment with linear power supplies. However, the harmonic distortion does not always sit well with equipment not designed for this type input waveform. So it is probably better to avoid it unless you speak to the vendor who's equipment is being fed by this UPS.
There are sine wave inverters on the market - though you need to carefully examine the specifications on these units. Some don't provide the type harmonic, RFI attenuation, and general power conditioning desired for high performance audio playback applications. The added series impedance should also be evaluated for suitability - especially if feeding a power amp.
There are high performance isolation transformers such as the MGE Topaz 100 which provide superb performance specifications, such as 140db common mode rejection, and feature a double shielded transformer with a UL rating for suitability in the medical industry.
Depending on the power quality and reliability at your specific location, the Topaz 800 may be better suited due to it's momentary ride through capability and superb harmonic trap and attenuation. This type conditioner does come with some compromises though, it is of ferroresonant topology and will emit bit more audible noise than a straight isolation transformer, as well as being a bit less efficient. It is best located in an ajacent or another room, perhaps near the power panel and feeding a dedicated audio circuit. It offers performance specifications that are often not found in the vocabulary of many audio power conditioners.
With any of these approaches sizing and suitability should be evaluated in order to ensure an optimum selection.
http://www.mgeups.com/products/pdt120/powerc/tpz100/t100.htmhttp://www.mgeups.com/products/pdt120/powerc/tpz800/index.htm
