Just on a whim, I looked up audio transformers in the 2007 Allied catalog, and they carry an interstage driver transformer, 10K to 10KCT, for plate to P-P grids. I'm surprised. 227-0862, 30mA max, 2" x 3-1/4" x 1-3/4", US $13.83 ea. (Price is actiually $14.91 today online).