Quote Originally Posted by Tony_Montana
Well, some AC problems a power supply can not overcome such as extreme fluctuation of AC. For example, there was a thread in HT forum where this guy was complaining about his light dimming when somebody was using the elevator in his building. For such instances, a power conditioner or UPS might be good idea.
In this particular case, a UPS is necessary because it is very unlikely that a power conditioner will work. However, one suitable for a high end audio system is usually very expensive. There have been a lot of complaints about the SMPSs in cheap ones causing more problems than they solve.