I think Violectric amps work well with a very wide range of headphone loads/impedances, and I know the V281 and V550 do. The V280 should as well, as it is very similar to the V281.
My V590 (which is a V550 with a DAC card) works very well with my high impedance ZMFs, and also with low impedance DCA Aeon (13 ohms) and Rosson RAD-0 (29 ohms) planars no problem.
I think you’d be fine with most all headphones with a V280. 
Check out this page for V280 specs/discussion:
Thank you, as usual, you have great beta for me! Have you heard the 222 by any chance? It looks like the 222 basically replaces the older 280 with “enhanced technical performance compared to the V280, offering greater resolution, detail, and transparency”. But, I’m wondering if it looses some of the warmth and tubey flavor people liked?
I’m just evaluating these variables as a value proposition. Used Vio 280 for $900 or a few hundred more for the updated 222 which may have changed it’s sonic profile slightly or Mjolnir as they are about the same price.
I’m inclined to go for the 280 and call it day.
I haven’t heard a V222, so I can’t give you any useful advice on it.
This sounds kind of analogous to the direction Violectric went going from V281 to V550, with some of the same description for how V550 differs from the earlier model…
What I can say is that it still has some warmth to it, but not to the same extent as V281/LE. It seems all their models have their fans, and I bet you’d be happy with a V280 if you get one. Their amps are really good. and extremely well built.
V280 is the same headphone amp as V281 but without the the balance knob and dual XLR outputs (which means that V280 cannot be used as a pre-amp unlike V281).
I have a V222 here. According to reviews, V281/280 has more power than V222. V222 however has a lower noise floor and also delivers finer details in a cleaner way. V281/280 is warmer, while V222 is described as “slightly warm neutral”, and V550/590 is described as “reference neutral”. The one that is supposed to be closer to V280 in terms of both power delivery and warmness is the V340, but it doesn’t have balanced inputs.
I don’t hear my V222 as warm. It’s warmer than e.g. the older SMSL and Topping models (no idea if today’s models are still surgically bright leaning). It gives a proper bass and treble extension to my DCA E3. I would still call it neutral, or maybe even slightly V-shaped compared to running from the Questyle M15 dongle (which is slightly mid-forward).
V222 drives most of the headphones without any problems. Some people reported that it cannot drive the Tungsten, the OG Susvara, and the HE-6 to their top potential, probably due to prioritizing voltage amplification over current amplification. I don’t have any of those headphones to prove it right or wrong.
Are you happy with your 222?
I bought my V222 as an all-rounder amp to power both dynamic driver and planar headphones to a decent level without coloring the sound too much. I think it’s serving that use case rather well. I would probably be more happy with it if I just had more listening time. It doesn’t get nearly as much time as my portable dongle which I use at work and on the go.
Depends on your use case and headphones you’re going to drive, really.