The LP and the V281 are both great amps but they do have different strengths and qualities. As you’d expect when comparing amps so far apart in price, the more expensive V281 has a lot more features and sounds great so if you can only have one and got the dough, get that one is what I’d say. The Cavalli is well nigh unbeateable at it’s price point though, especially when you throw in the potential for improving/changing it’s sound that tube-rolling offers. Good luck finding one for sale though!
Anyway, both amps have lots of power and their respective balanced architecture is really well implemented. If you don’t have or plan to buy balanced headphone cables then you’d really be missing out on the full capability of these amps. The LP has great detail and what I’d call an intimate sonic presentation. It really puts you close to the music but I think sacrifices something in terms of imaging and separation around instruments compared to the V281 because of that close up sound. That may be something that could be addressed with fancier tubes than I have right now though—I’m rocking the Genalex Gold Lions. The V281 puts you at a little more distance from the music but it is more dynamic than the LP. I can be listening to something on the LP with my eyes closed just kind of taking in the music and then I’ll switch to the V281 for the same song and seconds later I’ll find my head bobbing along vigorously to the tune without even thinking about it. V281 also does bass at a best in class level, though the LP is no slouch itself. So, does all this make them complementary? I can’t quite say. If I could only have the V281 and one other amp I’d probably go with a straight tube amp as opposed to the hybrid LP, just to maximize the potential of all the different headphones out there. But if I was trying to decide between a tube and solid state amp and looking to not spend a grip, then the Liquid Platinum is an easy best of both worlds choice. Bottom line though is that I can’t think of many quality headphones that wouldn’t sound great on both these amps.