boanerges

I recently retubed my CAE se3+ - it used to have Chinese tubes, but I replaced them (due to microphonics) with Sovtek 12ax7wb's. I believe that some of the harsh, compressed upper midrange and poor tone comes from these tubes. What's your recommendation - which tubes will be optimal for this preamp? Also, where is the driver tube located in these amps - there's no schematics available... Thanks! Boanerges