Just curious, but what are your thoughts on Babymetal?    

Actually both the ad2000 and the ad2000x are open back headphones. You're probably thinking of the a2000/a2000x, which are the closed back versions (confusing, I know). From reviews I've read, the main difference between the old and new versions is that the ad2000x has a slightly stronger bass...

I actually have pretty similar musical preferences to you (I listen to quite a lot of music with female vocalists) and am also in the market for the same sort of mid-forward headphones. I would definitely recommend staying away from the DT-990s. It has a v-shaped sound signature, and the mids...

I've been using my Headroom Desktop Amp/DAC for quite a few years now, and I'm wondering how it compares to the more recent Amp/DAC combos. Would the Magni/Modi stack or the O2 + ODAC combo be an upgrade?

I like the minimalist look! What's the sound signature for these?

They're just over the $100 mark, but I'd recommend looking into the Audio-Technica AD700x. I purchased the AD700x's predecessor, the AD700 a few years ago, and they were the most comfortable headphones I've ever worn.

1) Sennheiser HD650 2) AKG-k7xx/k701 3) Audio-Technica A900x 4) Beyerdynamic DT990

There were a few threads from quite a while ago discussing them and someone said they contacted fostex inquiring about a group buy. Did anything ever come of that? I've heard nothing but good things about the D2000, and it would be pretty awesome if the cans from the DX000 line were still available.