The BF 10 is a solid 200w driver and BF rate the cab as fiine for 500w so long as it stays clean.
Fully distorted a 135w tube amp is 270w of howling misery so not going to bother a BF 210.
Turn it up until you get to where another bump up sounds barely any louder. Turn it back down a nudge. If that isn't loud enough there you need more cab.
Putting the cab up on a chair or angling it up to you from the floor can make a big difference to your ability to monitor yourself with less FOH disturbance.
After they banned BassmanPaul I thought I better leave it alone for a bit before I got the ban hammer too.
B.P. is the most mild mannered gent you could hope to meet.
Tbf if you poke a couple of vintage JBL 15's with 50w they will get quite loud. With 500w you will get barely any louder but wind uo with a smoking pile of rubble if you aren't careful.
Lots of people gig with a Trace Elf that only has 160w into a 8 ohm cab.
There's no a guarantee that a 500w amp will suffice but I would not want to be in the same pub if it was required.
One thing to keep in mind when scoping out gear is the volume knob position is a poor indicator for how much of the amp is being used. Many amps are at full noise by the 4th indent with most of the action occurring between 0 and 3.
I think if you plugged in a 250W Trace Elliot amp, which is around 160w @8 ohm, it would get very very loud. Try your current amps out before over thinking it.
Another Stagg starter. I kinda wish I had kept it.
The purists can say it sounds like a giant fretless all they like. It sounded very DB to me so long as I kept the mwah under control.
Bill will tell you not to build that for bass guitar. It is a home audio enhancement device.
Bass cabs may say they go to 35hz but it's almost never 35hz that you can hear.
I did a bit of small venue sound for other bands once upon a time.
"Turn up the vocals!!!"
Me, pointing to desk of just single fader for vocalist engaged and redlined output.
"Feck they are loud aye!"
Me, nods.