Yep. The 4s were my first introduction to the planar world and BOY did I love them!
I offered them to my dad to keep them around (well, he's in France, I'm in L.A. now, but still
).
When I got the HE-500, I was using NFB-3.1 + Matrix M-Stage. The sound was so resolving, bigger and (much) lusher with the 500s that I decided to leave the 4s on the side.
Few months later I got the SA-31 amp and, out of curiosity, tried the HE-4 back on them. They scaled so nicely with power that they were not so far off the 500s anymore. Different tonality and overall take in the sound (clean vs lush) for sure, but soundstage and details were not behind the 500 anymore!
The 560 are everything I wished a more refined - and easier to drive - HE-4 would be. Fang and his crew listened to my wishes
.