I have a Packard-Bell SE amp in my workshop that I use for playing the radio. Can you post a picture of the amp? I have traced the schematic and can scan it if you have the same amp. It's a really simple circuit with a single 12AX7. One section in each channel, cap coupled to the 6BQ5 and global feedback. I'm using small old single driver speakers by Coral and the combo makes for a nice shop radio. For bigger speakers, better output transformers would probably be a good idea. The originals are very small.
John