Word.
From what I'm reading (example
http://www.headfonia.com/fiio-e9-dekstop-amplifier/)--and I agree with what I'm reading--it's a great amp that is very *neutral*. I was wondering how to describe it. It's very transparent. This is good and bad, depending on your cans, IMO. For example, I think most would agree that the HD 650's out of the box stuck on something neutral sounds kinda muffled up top and dark. something as neutral as the E9 will just make that sound louder. Same with the D7000. The highs are a little tighter, but still the same somewhat sharp highs.
Other amps change that sound, making up for some of the OTB issues, giving them that perfect sound. The same amps might make other cans sound worse. So it seems that it's all about finding amps that provide strength where your cans have weaknesses.
So for the 650's, I'd want an amp that warms and brings out the mids and adds detail to the highs. For the D7000s, I'd just want something that brings out the mids while softening the highs. I assume I won't find that in the sam amp now that I think about it. I think if Fiio had enabled the bass boost from the E7 on the E9, it may have made things very interesting.
TBH, the more I listen to the 650's exclusively on the E9 setup, the better they sound (ears getting used to less treble than the D7000). But I would like to hear something that will compliment them more. So I'm looking at the Woo Audio WA6 and a couple of others with an itchy trigger finger. I've been at this for hours. Time to take a break, I think.
Thanks for all the input, gentlemen.