Running a bass pre into a PA power amp was the defacto rack rig for over two decades until the mini amps became the rage.
I run a Kern IP-777 high-voltage all-tube hand-wired bass preamp with NOS tubes into a QSC PLX3602 power amp (which is a typical PA power amp), and it is the bomb.
If you want good tone, I highly recommend that you stick with preamps that use high voltage in their circuitry. Some companies shove a 12AX7 tube into their preamp at low voltage just so they can tout it as a tube pre. Don't be fooled by such tripe. Stick to high voltage (~300v) preamps such as:
- Kern IP-777
- Alembic F-1X
- BBE BMax-T
- Avalon U5
There is a reason those sound so much better.....it's the high voltage.