S.RTRV stands for 'sound retriever'. It automatically enhances compressed audio and restores rich sound. It adds a little boost to the far ends of the frequency response.
The way audio formats such as mp3 work is that they remove audio data that most people can't hear, this means that up to 90% of the audio information that was recorded is removed; this results in a much smaller file, but sacrifices quality, which may be particularly noticeable by the lack of high frequencies in the audio.
The S.RTRV function attempts to bring the highs "back to life," and make the sound more pleasurable to the ear.
Tip! Crutchfield.com shares 12 tips for getting the best sound quality in your car.
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