This is in principle possible but I am not sure if anyone has tried it. Killian Lackhove (one of the senior developers) has been using base flows from another solver to solve the acoustic perturbation equations. He has implemented a range of FieldConvert option to interpolate cvs data to a field file which could in then be read in as a base flow. The issue will be if the resolution of the base flow is then sufficient accurate to allow you to pick up the correct instability mode but it is worth trying to see.

Cheers,

Spencer.