Krell KST-100


I have a Krell KSL preamp and am talking to two sellers about possibly buying their KST-100 to match it.  Flavor note - I'm currently running a Proceed by Mark Levinson AMP2, which the KSL-100 may not beat, but who knows?  The Sickness has me. 

I have read that the newer models are substantially better than the older ones.  I'm hoping to find a 1992 or 1993.  I have serial numbers from the sellers, but they don't seem to conform to other posts' explanations of deciphering them.  Anyone know how to "date" the KST-100? 

Grateful thanks.
atticus-xi
The KST is a Class AB amp, not having the heavy Class A bias typically associated with most Krell’s. IMHO, not a bad amp, but a cheaper Krell not really up to the standard of most of their other amps.
I just spoke with Krell's service dept. and apparently they weren't yet tracking serial numbers in those days.  Anyone know identifying features of the 1992 or 1993 KST-100?