I've owned two Lincolns with JBL sound systems and IMO they are awful. The only way to hear much bass and treble is to boost the controls which makes the bass boomy. The CD player is a Sony with a 10 disc changer mounted in the trunk. If you hit a bump the laser loses lock and the only way to get it to play again is to stop the car, eject the disc holder and re-insert it. Radio reception is not very good and there's no way to defeat the stereo multiplexer when the signal is weak. A poor product IMO.
Harman Kardon's claim to fame were its Tube Citation units I, II, III, IV, and V still very collectable and its Citation 15 and 16 preamp and power amp. I think those were the ones designed by Mati Otalla after he discovered slewing rate related distortion (Transient Intermodulation Distortion.) I've got an old A500 amp and F500X tuner, my first components. Later on I was sorry I didn't buy Dynaco PAS 3X, Stereo 70, and FM 3 instead. I had a lot of problems with the F500X originally because it kept drifting out of alignment. My main system has a Citation 11 as its main preamp because of the 5 band equalizer. About a year ago its 1000 mfd 100V power supply cap gave up the ghost. I replaced it with what I had around, two 4800 mfd 75 V Mallory caps I wired in series. It never sounded better, the original cap was undersized.
Infinity's claim to fame was the original ServoStatic I ($1800) and 1A ($4000.) These were triamplified hybrid large panel electrostatic systems. A single large servo driven subwoofer was suplied with a 250watt amplifier, very big in its day. Most are probably no longer operational due to failures. The other speaker of note was the massive IRS and IRS beta (orignally $50,000.) These were designed by Arnie Nudell. Four ceiling high towers, two containing vertical arrrays of EMIM midranges and EMIT tweeters, the other two towers containing six 12" woofers each. Arnie went on to Genesis where he manufactures a similar design that's much more expensive, I think around a quarter million. Also noteworthy were Kappa series, 7 and 9 were popular. They also used EMIM and EMIT drivers. This was all before Harman acquired them.
JBL's fame was and still is in professional sound reinforcement systems. Two noteworthy models were the Hartsfield, JBL's answer to Klipsch and the Paragon which is the most unusual speaker I've ever seen. JBL came strictly from the west coast movie industry driven school of theater speakers from which Altec Lansing also sprang. K2 looks to be some kind of redux of the Hartsfield although I don't think it's intended for corner placement. I don't know the current price but I think it was introduced at $50,000.
http://www.audioheritage.org/
http://www.audioheritage.org/html/profiles/jbl/paragon.htm
When it came to high fidelity for the home though, I'll never figure out how JBL managed to combine the best made drivers in the industry into one awful sounding speaker system after another.