EB string are the only brand I used to break so I haven't owned any since the late 90s. I was using the pink packaged super slinky's O think.
After some years of searching I've now landed on DR strings and haven't had a set disappoint me.
If I were in your position I'd play the current strings to end of life to see how long they last you. Everyone has different amounts and composition of skin grease on the fingers, some more acidic than others and this will make a big difference.
1st and last fret depress is the way it's done, but you said some companies do 12th or 17th fret which is weird. What companies depress 12th or 17th fret? Id like to know so I can avoid them.
https://shop.warwick.de/de/ersatzteile-fuer-instrumente/warwick-ersatzteile/bunddraht/warwick-parts-brass-frets?c=3572&number=D0903032001564882613A1894-A00000018886
You can order a set and have a local luthier put them in the bass of your choice.
The pre reminds me of the hartke ha3500, clean and barely any character which is perfect if your sound comes from your fingers, your bass or your effects. The d.i. works in the same way. I wouldn't record through it but it's fine for live signal to front of house.
Typical Harley Benton I'd say, functional without much fanfare, for a great price.
I have a HB 800b as backup amp. It's fine, responsive to EQ, has the standard poweramp as all 800w class D so power in excess. Less than 2kg I think and easy to pack.
If you want tube sound or drive you will need a preamp.
I'll make an offer of what I think is a price I'm happy with. Then it's up to the seller to accept, reject, or suggest a new price. I can then accept the outcome or stop the negotiations, any further haggling I would consider rude. In this process everyone has had a chance to name their price point and that's that.
What strings are you using and how old are they?
What's the rest of your signal path, preamp straight to desk or to an amp? If so what amp and cab? What other effects on your board if any?
Hellzero has a good point about the ears, ever done a hearing test?
DR strings like the low riders are a bit stoffer. Gauge has very little to do with it, the shape of the core of the string however is relevant.
A hex core string feels different than a round core even though they are identical on the outside.
Any strings that have something like "higher stiffness" in the description will work nicely.