@audio2design - Garth Powell (Audioquest) talks about current compression in power amps and its effect on sound in his "Power Demystified" article (link above), an excerpt of which is presented below....
There is an additional problem: In order to cover enough range, a
passive filter will require some inductance (the “L” in LCR), which will
raise the AC impedance somewhat and create a phase lag for power
current transients. This is of no consequence to video, computer, or
source audio components, as they utilize low-amperage constantcurrent circuits. However, this can severely current compress a power amplifier as its power supply draws down to supply an audio transient, while the power amplifier itself requires a large influx of current
to its power supply to maintain low-distortion operation.
To get around this issue, many passive AC power filter/conditioners
will isolate the circuits that utilize any series inductance for source
components only. The circuit without series inductance is set aside
for the “High Current” power amplifier outlets. If a power amplifier experiences current compression, the sound that results from an audio
system can be described as thin, anemic, muddy, and slow, while the
soundstage tends to collapse or pull with frequency during dense or
modulated passages.