I would agree with @peteb with his words of caution, I think it was lending a bass to someone who cranked the bass? 18db boost isn’t always what your amp and cabs want!
however... j-retro and uni pre are different... j retro by standard has a bit of a bass boost pre-shape baked in. Uni pre you can defeat this,
uni pre also has the ability to set thr upper and lower bounds of the bass boost... so you can set where this isn’t boosting 20-80hz from memory, and also set the top end. In my Lakland the bart pickups have quite a lot of low mids going on thst can sound very fat and muddy very quickly - so my bass boost is set up to boost everything below the gank and not the subs.
I love it. But would agree with Pete B that it’s not for everyone.