i used to have one, since the 70s up to a few years ago;
it was always connected to my audio system.
this is how i discovered that my Hafler 500 amp had an instantaneous
power output on music peaks of 735 Watts/ch.; pretty good dynamic headroom. Rated continuous power was around 250W/ch/8 Ohms.
sometimes, as a show to some people, i used to connect the LF and the RF each to an oscilloscope input; that would show phasing between the 2 channels, and it made for an interesting visual rendition of the music that was playing
