Update to what I posted previously (quoted below)
My ears weren't fooling me after all. It turned out that the reason I was thinking the 194s were not bright enough was caused by defective polyswitches, especially in the left speaker. The polyswitch in the left speaker had 21.4 ohms resistance and the right had 4.2 ohms resistance effectively attenuating the tweeters in my recently acquired 2Bs. The slightly brighter sounding (to my ears) sl2000 was helping offset that some. Once jumpers were installed across the polyswitches the 194s sounded the way I thought they should.
I just thought I would pass this on in case someone has the same problem in the future.