The best replacement for coaxial speakers is component speakers.

The best alternatives to coaxial speakers are rated as following:
★★★★★  component speakers
★★  2 way
★★  3-way
★★  triaxial
★  component

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Speaking about coaxial speakers, one probably shouldn't forget about tweeters.

Other search terms related to coaxial speakers and their ratings are:
★★★★★ tweeters
You have in mind a companion for coaxial speakers and it is not yet here? Propose!



Google Trends

Scale is based on the average worldwide traffic of coaxial speakers in all years. Click on graph for more.
coaxial speakers
component speakers
2 way