BeachTek DXA-SLR PURE Operating Manual page 13

Notes on Getting the Best Audio Performance
The most common problem in recording professional audio on today's
DSLR cameras is the hiss generated by the camera preamplifiers. You
will never completely eliminate all hiss, which is normal, but you can
reduce it so that it is no longer a problem.
The most important thing to remember when recording audio is to set the
audio levels correctly as explained in this manual.
Setting the levels too low will give you a poor signal to noise ratio and
lead to poor results. Also, setting the levels too high will cause clipping
and distortion. Having the proper levels will ensure that good clean audio
signals are being sent to the camera for the highest quality audio.
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