Hey fruit,
I'm sure it can be argued a million different ways but I think almost all preamps color the tone to a degree. I will say however that Bartolini does have a distinct Bart sound and that me be what your hearing .
I have used the obp3 but not the glock. I used it in a franken mm bass I was toying with a few years back along with a bartolini mm pickup. While I would say the aggie was fairly transparent it still changed things a bit. I would call it (up for argument) a very modern sound.
I've read a few reviews on the Glock over in the Roscoe forum a few guys love em. There supposed to be even more transparent and may be exactly what your looking for. Others have tried the Audere and again while its transparent I think the consensus is the Glock is better overall.
Out of curiosity were the Aeros custom made for the bass?
Blessings