The best replacement for line conditioner is voltage regulator.

The best alternatives to line conditioner are rated as following:
★★★★★  voltage regulator
★★★★★  surge protector
★★★  isolation transformer
★★  avr
★  power conditioner

Your alternative for line conditioner is not listed? Suggest!
Speaking about line conditioner, one probably shouldn't forget about ups.

Other search terms related to line conditioner and their ratings are:
★★★★★ ups
battery backup
You have in mind a companion for line conditioner and it is not yet here? Propose!



Google Trends

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line conditioner
voltage regulator
surge protector