Hi, thank you for contacting JustAnswer.com. My name is Russell. I will do my best to provide the right answer to your question.
That sort of loudness distortion is known otherwise as 'signal clipping'. It happens when an amplifier input is overloaded, to the point where the waveform of the sound going in become nearly a square wave. Which makes it sound both 'buzzy' and slightly muffled or distorted/details of the sounds lost/etc.
If the input to the amplifier is set too sensitively, this can happen.
But also, if the output of the device or microphone going into the amplifier/input, is too loud, or set too high.
So if you have been adjusting it on one side, try adjusting it lower on the other side for sure.
If adjusting both sides downward cannot help with this, perhaps the sound source is not suitable for the Tascam device's input. Let me know more specifics please, and I will advise you further as to what to do. (I would guess a a glance, though, that you need to turn the CD player down, its Volume down, a lot.)
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