Originally Posted by DiabolusInMusic
Stop putting money into it and invest in a better bass. If you only have $100 to work with, put it in a jar and start saving it.
The GIO line is entry level and it shows, their B string is unbelievably sloppy to the point it is almost unplayable. The bass isn't worth much more than $100 now, if that, so if you put in another $100 you have a $200 bass that is worth $100 on a good day.
If you insist on modding that particular bass, start by changing the pickup. They will be one of the cheaper upgrades and offer one of the largest changes in tone in my experience. A blend knob blends either two pickups or electronics and piezo, a blend for one pickup will do nothing other than spin.
I own a GSR 206 and it's a killer bass that I bought for a song, though it could use some new pickups (they don't quite cover the strings), but yours is a different case. It only has one pickup to begin with so "blend" is out. And unless you are aware of a pickup that will fit that route, I'd say leave that exposed pole pickup in there. I should sound reasonably decent if EQed right. A new pickup might be a hassle to fit and unless you have some favorite pickup in mind that you KNOW the sound of, you may end up with something that sounds WORSE than what you've got!
It's a one pickup bass so it's never gonna have the tonal variety of a dual pickup bass. It's like Ibby version of a P-bass. So instead of trying to make it into a different bass, the key is to tweak the sound as it is until you love it. One bass, one sound. And leave it that way. Just accept it. It's OK if that one sound is KILLER! Get it?
So instead of a new pickup I'd be trying to FIND that one sound in that bass. Spend that money trying different strings. Try flats, try rounds, try ground wounds. Try brands TBs recommend and love (especially on basses with basswood bodies) And then take the rest of the money and get a cheapo Chinese active preamp off Ebay for it. If you get volume with stacked bass/treble, you won't have to drill new holes which means IF you ever sell the bass you can put it back the way it was (save the parts you remove in the gig bag). Doing this will not only be educational but also give you a good chance at finding that "killer" tone. Don't worry about playing the bass with EQ cranked all the way up IF that gives a tone you like.
That's what I'd do. You COULD make a bigger project and install two pickups, preamp and the rest, but I don't think the basic bass is worth the expense of effort. You'll never get the money out of it later, so try to make improvements without spending a tone of cash that will never come back.