When I plug an amp into a good 4x12 or OS 2x12 - there is a good deal of bass and some of that thump - even when played clean - when played at a decent volume.
I feel I'm missing some of that with the Fractal models when played through those same physical cabs. It is there on some of the models (eg: JTM45), but on many others, I feel its bass-lite. This dramatically affects feel. I can dial some of what I like with the EQ, but I'm wondering why many of the models seem a little light on bass. Anyone else feel this way?
Another thing that I noticed is that on the jumped Marshalls, the 'tube breakup' (don't know how better to put it) seems too early and overly distorted at higher gain levels. I don't notice this on non jumped models.
I feel I'm missing some of that with the Fractal models when played through those same physical cabs. It is there on some of the models (eg: JTM45), but on many others, I feel its bass-lite. This dramatically affects feel. I can dial some of what I like with the EQ, but I'm wondering why many of the models seem a little light on bass. Anyone else feel this way?
Another thing that I noticed is that on the jumped Marshalls, the 'tube breakup' (don't know how better to put it) seems too early and overly distorted at higher gain levels. I don't notice this on non jumped models.

You're apparently too young to be aware. The saying is an old chestnut that was quite correct at the time. Look up "Bose 901."