As an electrical engineer I can only say none of the so called pure sine wave commercial 1 phase UPS can provide you a pure sinewave as even a small kerosene engine driven genset can. They don't turn in a magnetic field like an AC generator in a perfect circle to produce a sine wave. All of them chop the DC and serve a chowmein of harmonics whatever filter they use.
Unless you have a 3 phase isolation transformer with delta connected primary and star secondary you are not going to eliminate fully the harmonics generated by the chowmein supply feeding into your gear. And for that you need a 3 phase UPS.
And those poor transformers inside are designed to work on 50Hz will have to gulp down 100, 150, 200, 250, 300 Hz etc. at differing "strengths" and get "drunk", get hot and die a premature death due to many kinds of electrical cancers - insulation failure, internal shorts, core over heating, winding failures etc. etc.
So I don't think these pure sine wave are the holy grail.
Always a stable network power is the best sine wave you can get. The generation behind your "disgusting" EB power is in GWs (In India something like 300 Giga Watt so where is your 200Wpc amp?). It is an infinite bus.
The surges you experience is many a times beyond the control of any power utility - mostly lightning or fault induced or by your neighboring workshop doing welding or a furnace in the industrial park throwing load up and down.
For these surges as
@mbhangui explained or
@ranojoy pointed out you need a proper surge protection. Or you'd have "fryums" made of capacitors, resistors and chips on your AV rack. Stabilisers may not act fast enough to tame these surges. They can't as unless there is a steady state rise in voltage these deviations may be in their deadband. dv/dt has to match the inertia they have.
You also cannot purchase any power strip and assume it will not get fried. These lightning surges though last only a few micro seconds the energy is unbelievable and so too the effects may be benign or devastating.
The power strip should be able to take in the energy so you need to choose as high as possible in the order of 1kJ. Once the MOV is fried and open, the surges have free access to lick your gear with their fire.
You also need to look for a 3 line protection - Line to Earth, Line to Neutral and Neutral to Earth.
I was eyewitness to a lightning bolt getting to the ground two times - once through a 50m lightning mast and another through a ground wire up a 400kV power lines. Beautiful sight but we had no cameras or mobile phones those days to record
It had 3 line protection it seems.
