I think i have a idea on how it is wired...
most of the audio transformers I have wired up were either single primary and single secondary, or single primary Dual secondary or single primary center tapped secondary.... Yours looks like a dual primary and dual secondary with a ground tap (pin 9)....
The way I see it you have a few options of how to wire it...
You can wire both the primary and the secondary in series....
(on the primary side the Ina217 Preamp output connects to pin 1 ,Pins 2 and 3 connect together ,and pin 4 goes to ground, On the secondary side Pin 5 goes to + out, pin 6 & 7 connect together and go to ground ,and pin 8 is - Output)
You can wire both primary and secondary in Paralell...
(Pin 1 and 2 connect together and connects to ina217 preamp output, Pins 3 and 4 go to ground, 5 and 6 connect together and are + output ,7 and 8 connect together and are - output , 9 goes to ground)..
You can also use a combitation of Series and Paralell of each primary and secondary and you can also wire a switch so you can go from series and paralell on each winding...
As for which wireing method is suitable for you I don"t really know but I would first try wireing both Primary/secondary in series and see how that sounds and go from there....
Cheers