HD560S sound signature is little bright when compared to 6xx or 598. bright neutral kind of signature. HE400se will be a similar kind of bright signature but there will be a difference of planar magnetic driver vs dynamic driver sound. i believe resolution will be slightly better with 400se.
The catch is 400se is low sensitivity and low impedance. it need proper desktop level amplification to to get its 100 percent potential. you can use lower powered amps but still. 560S will be a lot more easy to drive. In my case as i lok for warm sound i wil not be choosing both but if i have to choose among these two then i will go for 560S as it is made of dynamic driver and more easy on the ear sound than the 400se
