The LO1166 is normally wired series:series in all the class-A stuff. But Thomas, if you hooked it up to the 1081 output (a BA340, yes?) like you would an LO2567 (parallel:series, I believe), then you're getting more like 10dB gain instead of the 4dB gain it produced in the class-A circuits. Perhaps being wired for this kind of ratio really emphasizes the effect of the inductance loss of a gapped design? Just a guess.
Tom, what is the ratio you'd want to use with the 99v? Series:series the LO1166 is 1:1.7 (4dB gain). I really don't know anything about what kind of performance to expect hooked up any other way.
CJ? PRR?
JC