You know, if you're wanting more thud and less roundwound boing (what esoteric terms ! ! ), you might want to check out the Thomastik strings they developed with Rick Turner for his Renaissance axes.
Turner rightly figured that axes that were piezo-only (like his or your Ibby) did not need any metal in the string, the piezos were reading vibration from the plucked string. So they have a nylon core. Not cheap from what I understand, but might be a tweak that would help out here.
Fives and Sixes with that low B will teach you to fine-tune your pickup heights, they can really boom out on some basses. Smart piezo axes feature the trim pots you axe has to ride the overall gain, but also to fine-tune the string to string balance, which helps with the 'B Boom'.
I like the rounds on my Sire NOW, even aged they offer a bit to the tone that the rotosound flats on my P-bass don't. The Ibby has flats on it, but the accoustic feel of the bass and perhaps the gain settings on the piezo it has been the brightest sounding bass I've ever personally played. .45-.105, I can be happy with new or old strings, round or flat, prefer some age. The low B so far, at least at .132 and .135, round on the sire, and the flats on the ibby are too touchy fresh out of the package for me so far. For the sire, and the particular set of strings the fresh out of the package low B was my only disappointment, made adjustments to my pickup heights to no avail but after time the overtones I was hearing when the strings were new faded away. The notes on that B sound tight now.
Aside from truss rod and saddle height adjustments however, with the Ibanez I believe there must've been some factory set up as out of the box the string volume itself when playing notes seems rather even, and the only string I had to adjust intonation on was the B. That's part of why I haven't fiddled with the gain switches for the piezo, as aside from my own fumbles with the B, to my ear, they sound very even.
It's just even when the strings were brand new on the Ibby, the B sounded freaking tight when I actually played it rather than attempting to mute it. Not boomy. Sounded good compared to my experience with bright rounds fresh out of the pack on the sire and the nutty overtones. I've kind of attributed that to it being a .135 round labeled "bright" fresh out of the pack lol vs flats which are going to be less bright. I'm good with the sound of my strings on all 3 of my axes currently.
I'll cross the bridge with the gain switches at the jamspace on Sunday most likely to try and get it close to the output of my P-bass and Sire, which I've been playing in passive mode while we're recording as I'm also using the P. Ibanez recommends the specific set I'm using due to the piezo, same strings that come with it stock. But I'm interested to look into the Thomastiks at some point down the road to see what's up with them.
Appreciate your input.