It's just a different feel really while you're playing, and it's not lag like you think of it, they don't take a split second to actuate the speakers, in an ideal world the speakers stops almost immediately after the note stops, which a sealed cab like you have helps with. If they stop too fast (to me) the sound is what I call dry, I like just a little give and take which is probably why I like tube amps better. I play the amp as much as I play my bass. I do own a few SS amps too but can tell the difference when I use them. I'm no expert at this I just know what i like but struggle to find technical terms to describe it.