Professional audio equipment assumes a supply within a defined window. Across much of India that assumption does not hold reliably, and the equipment that suffers is the equipment left connected during the excursion.
The damage is cumulative
Voltage swings shorten the life of power supplies well before they cause an obvious failure. The damage accumulates quietly, then presents as an amplifier that fails early for no apparent reason.
What to specify
A stabiliser sized for the rack, with auto-cut protection, is a small proportion of system cost and removes a whole category of site problem. In installations that run daily and unattended, it belongs in the drawing rather than the maintenance conversation.
