Well, I'd still rather listen to the HE-6 out of my little EF5 amp than the HE-500, even if the HE-500 will play louder. However, out of my ZDT amp the HE-500 scale up very well and then if I use a nicer cable the HE-500 get even closer. So, I still think the HE-500 do best with a powerful amp. That sounds like basically what you are saying (when you say properly driven), but my favorite amp for the HE-500 is still quite costly. If all I had was my DACmini or WA6 I'd have to go with the HE-500, no question, but some low end amps do very well with the HE-6. The HE-6 with HE-adapter out of my 40 watt Marantz sound pretty darn good too, and for a lot less money than the HE-500 + ZDT amp. Which wold I recommend? I don't know anymore - they're both good phones.