Diff_Rev00x sub-pcb with the gar1731 DOA

Hi

Installed the Diff_Rev00x sub-pcb with the gar1731 DOA on one of my Tac Scropion I S-1000 channel strips.
It has a high background hiss when you start cranking it up, and when you use the Hi Freq  EQ its worst.
I don't know if this is normal for this mod, I sure hope not. The tone is very good, if you keep the level down and not use the Hi Freq Eq, it sounds pretty good. I re-soldered all the joints just to make sure there were no cold solder points. 
Please let me know if someone has used this combination in there Tac Scropion I
Thanks Tony

Hey Tony,

I never picked this up back when you posted your problem, did you figure out what the problem was?
I hope you figured it out by now, sorry to let you hanging like that, I guess it will have been a thing with
the opamp itself?

Kind regards