What's wrong with a Mark Bass Cab?
Since you already have a MarkBass LT 800 I would try stacking a Markbass 210 on top of a Markbass 151. I have almost the same setup, but instead of a Markbass 210 I have a Mesa PH210, and instead of a MarkBass LT 800 I use a GK 1001rb II to power it. I like it and I am sure you would be able to more then be able to cut through. One of the guitarist that I play with uses some Marshall 412 set up, and he whines about my GK/Mesa/MB setup every time. The other guitarist plays through a H&K Tubemister 18 and a Orange 212 cab, and the GK/Mesa/MB holds its own against that set up. I think a Markbass 210/115 setup would sound better maybe, because both of those cabs have the same wattage (400/800 watts max) so they would be evenly matched. The way my cabs are is the Mesa PH210 is 600 watts and the MB 115 is 400 watts, IDK though it's probably not a big deal because like I said I sounds killer to me and everyone else that hears it checks it out and gives me a thumbs up. I am just a bass gear junkie, you probably better off listening to the more seasoned bass players here, that's why I'm here.