That is a very different question from the one you asked.
'Most' amps will let let you line in via the fx return. I think it's more usual to have the onboard DI taken from before that point but even it it isn't the original question is moot anyway because you'll never know until you get there.
It seems what you are looking for is a comprehensive preamp with its own DI out and line out. If you set it up with a PA friendly sound and use the stage amp front input for monitoring you're all set.
There's many ways to skin that cat depending on whether you are using fx and how coloured your own amplification is. You might be looking at a new FRFR rig for yourself to go with the preamp.
Beware the rabbit hole.
A lot of tunes you will find the note for note bassline only properly grooves if the rhythm guitar cops it right on. Drums also. As soon as one of them wings it you can forget about note for note.
Generally it takes the guitar player to get with the programme and then the drummer will fall in.
Once upon a band jam both my feet left the ground simultaneously. There is no other way to describe it. I didn't jump, I was lifted up by the music. I can't fake that.
Challenge accepted.
I have played a few weddings but I don't consider myself all that flash as your average wedding band bassist.
Playing straight quarter notes perfectly is a lot harder than it sounds. Walking at the same time ramps it up some too.
About 180BPM for me. It's right there on the chart! If I was to set to 220 I could probably mash it out leaving out the twiddly bits.
That'll work so long as
1 the aforementioned cone breakup isn't required.
2 the amp isn't one of the new breed with classD power stage tuned in breakup. Some cabs can be rewired to 16ohm to help out there but I wouldn't bet on it solving the neighbour problem because those amps are all 600 to 1000w afaik.
As an early morning brain exercise I am putting my non electrical third eye to work to build the chocolate block crossover. Through the fog I think it requires 4 screws each side?