Properly amped, the HE-6 can be the best headphone in the world. It was the HE-6 that made me buy a SX-1980, originally. I wanted to be able to deliver enough power right from the headphone jack. And the HE-6 paired with the SX-1980 is pretty special as a combo, I will tell you.
The sx-1280 is the first amp that I feel gives the he-4 enough power to sound like it's capable of. I thought that the lyr was enough...it wan't. Even the 9090db can match "excite" the he-4 like the sx-1280 is able to. This combo is the first real "Ah, I've arrived" moment that I've had in quite some time.