Threshold Fet One

I have recently aquired an old Threshold Fet One Preamp and I would appreciate any information regarding it. Maybe a manual or specs ?
Threshold's 1982 technical information sheet devotes an entire page (of three) just to the model FET one. Here are the specs:

phono section:
Distortion: Less than .01% at 5 volts preamp output into a 10 kOhm load

high level section:
Distortion: same as phono section
Slew Rate: 25 volts per microsecond
Rise Time: 2 microseconds
Supply Rejection: -80 dB
Overload Point: 14 volts preamp output peak
Preamp Output impedance: 470 Ohms.

Enjoy your new preamp.
Thank you. Do you know how I can find Threshold's 1982 technical information sheet?
I suggest you call Threshold Corporation and ask them. The web site is
savourdos.. hi, if you already got info about FET ONE please send them to me too. Cause I have one of this kind. and I don`t neither know its specs.
my mail: thank you.

i have this preamp working with a Nakamichi Pa7 power amp (STASIS too)but i`m plaining to go to tubes ( AUDIO RESEARCH D125) I `d like to know if this is a good idea or not.