They’re different. Both good, I think the Sennheiser are comfier, but this is very subjective…and the SENNHEISER hd 560s? which one do you think is better the 400se or the hd560s?
What’s not subjective is that the 560s, at your budget point, would be a great choice in the active driver department to complement your planar.
Unless you can buy from drop in the US, and get a pair of HD6xx, there is no other product, as far as I know, that offer this level of detail, good frequency response (a refined FR respect to previous “HD5” headphones), fantastic comfort in a tossable shell that will sustain heavy use, all at around 200$.