Yes. The efficiency runs very low, which means they generate more heat than designed for, and can possibly blow devices in the power supply. If an item is designed to run on 14 violts, it needs 14 volts...
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It all reminds me of something that Molière once said to Guy de Maupassant at a café in Vienna: "That's nice. You should write it down."
Why are you getting 10 volts or so at your amps? I believe it will put will put strain on them, yes.
If you are, your amps should be the least of your worries, the car's electrical system (brain included) are at risk!
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nah i wouldnt worry about it. Unless you run the amp on a constant 10V for several hours... GOOD amps should be able to run as low as 9V and as high as 18V without issues (unless you are running a very low ohm load, lower than what the manufacturer designed the amp for, then your amp may not last that long).
Most good amps have a thermal overload on it as well... do you know if yours does? What amp is it?
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04 dodge neon SXT
(2) Oz Audio Matrix Elite 12"s sealed in 4 cube fiberglass enclosure, powered by HiFonics BX1605D
Oz Audio Matrix 180cs 6.5" component set power by HiFonics ZX4000