Using Low votage audio amplifier with a load cell
Audio amplifiers in general aren't appropriate for amplifying load cell (strain guage) outputs.  This is because audio has a lower frequency limit.  Most audio amps will block DC or expect their input to be AC coupled thru a capacitor.  This is fine, even desirable, for audio, but not good for the very low frequency signals coming from strain guages.

It is possible that some "audio" amplifiers are DC coupled, especially if they are just chips.  However, these may still be difficult to use as general instrumentation amplifiers because the DC offset was not a consideration in the audio application.  It is probably fairly large and maybe not even specified because nobody would care when the device was used as intended.  There may also be issues of input impedance.

What you want is a instrumentation amplifier or at least a precision opamp.  Which one you need depends in part on how the sensor is arranged and what exactly its output signals are.  Some are differential, in which case the instrumation amplifier would be best.  These amplifiers have high input impedance, known fixed gain, and real differential front ends (meaning good common mode rejection).

We can probably be more specific if you explain more what exactly is coming out of your sensor.