The C-91 control amplifier was introduced by Pioneer in 1989. It featured a subtle change to the front panel controls.  The nomenclature of the first button on the left under the Video Input bank of controls was changed from  TV Tuner to TV/AUX.  All other controls were unchanged. Of course, the ELITE name now appeared on the front panel.

Perhaps the most significant change between the C-90 and C-91 was the price. The C-91 was a whopping $500 more expensive than the C90, with a MSRP of $1300.00 when it was introduced.  It was manufactured through 1994; the C-91 was not listed in the 1995 Stereo Review Buyers Guide. The only control amplifier in the Elite for the rest of the decade was the C-72.

Note: The C-91 shown here is part of my personal ELITE collection. The Webmaster

C-91 with front panel in open position