Going off topic a bit, when I was in a hardcore band back in the early 90s, and we went into the studio to record, the engineer would give us rough mix downs of the music to go play in our car stereo as a quick check on it. In the recording studio with those high end studio monitors, it can make things sound far different then the more average sound system most people have access to.
I'm into it. Sounds a bit like Silent Majority (Long Island band), who I believe would have been your contemporaries although this is all before my time so I'm speculating.
It's standard practice - every producer or engineer worth his/her salt will some some version of this. Many engineers keep cheap boomboxes or crappy speakers in the control room for exactly this purpose.
