Bass Amp Upgrade

I fretted and fretted (no pun intended) over my amp. I ended up with a 150 Rumble. I can get pretty much tue sound I want from it. I have looked for another amp, for the same reason you cited. I even played with building a cabinet, then getting a head to drive it, but the long and short of it is the Rumble does its job. It is fun to fantasize about upgrading equpiment though.

Boppa

Would also say stick with the Rumble
I've also got the same unit and do use it for live jam sessions a couple of times a month and it sounds great with more than enough power for a village hall that we hire
Also very impressed with the built in overdrive channel and punch settings ,got mine cranked right up for a filthy tone
As you know the Rumble is a bit of a beast for transporting around due to its size and weight so I use a sack truck for transporting mine with a pack of beer on top for the 10 minute walk to our venue (don't drink n drive kids) so imagine the issues you would have with a separate head and cabinet
My bass is the epiphone T bird pro with active pickups so between the two I can get all the tone I need
The better sound you are after will come as you improve your playing ability so keep your gear so keep practising and save your dosh for beers, that's my mantra!