BTW, I should probably mention that companding is the combination of compression and expansion of the audio signal levels.

Compression lowers the higher signal levels and expansion raises the lower levels. Companding makes the overall signal level more constant and is unnatural sounding with even more lack of dynamics. The "pumping" and "breathing" is even more noticeable than compression because during lower level passages the signal to noise ratio is less (less signal, more noise by comparison) and boosting the signal also boosts the noise by the same amount. Compression alone produces pumping and breathing because the result of lowering higher levels also makes the lower levels (and noise) louder by comparison. In cheaper compressors the pumping and breathing is more audible, in really good high end compressors it is barely noticeable unless too much compression is used.

It's easy to make good gear sound bad. It's an art to make mediocre gear sound good.