Yeah, that's the conclusion I came to.
My previous, previous setup was a budget one, around 500$ [namely, the NFB-3.32, a warmish DAC and an Emotiva X-a100, a fairly neutral amp] and the HE-6 was good but not great or amazing.
I am willing to bet that HE-560 would perform quite a bit better off that setup.
My previous setup, a roughly $500 Compass2 DAC/amp sounded pretty great with the HE-560 [but wouldn't with the HE-6 due to lack of power] and my current mid/hi-fi SA31SE/NFB7 sounds even greater with the 560, so it certainly scales up too! [and will with the 400i as well, no doubt]... I'd have my doubt with the HE-6 though as it is a fairly neutral setup and because the HE-6 was already pretty bright with a kinda warmish setup... Might have been even brighter now.
I guess what I am trying to say is that with the HE-6 you ideally want a warmer setup [which yours setup kinda is, except for the NFB, maybe].
But what do I know? Maybe I'd be wowed with the HE-6 if I purchased it again, as this was a year ago.
Still, I think I'll wait for its successor or the Jade II for now... HE-6's very low sensitivity with its bright nature and high revealing/scaling ability is an advantage for some but a downfall for others.
TL
R - The HE-6 is a TOTL headphone that coupled with its very low sensitivity and bright nature requires very serious tweaking which is not for everyone.