Sennheiser HDVA 600 if you're looking at that route then look at a used HDVA 800. You can find one around 1100. Between those four I'd go with the ha 200. It has plenty of power and the most neutral response.

I've had no problem with the bass on my HD600s. They'll drive them fine, and really bring out the headphones. If you're really looking to bring the most out of those cans I'd definitely look at the dual mono options. A for one unit you'd just have to try one. The hd800 gets picky about what amps...

Any quirks with the setup really. Also, what's a nice DAC to go with them? I was looking at the Emotiva XDA-2 2nd gen.

Any new updates on running these things balanced? I've got one, and am looking at getting a second, but it needs to be worth if for how convoluted the setup would be.

Anyone have a comparison to the Sanskirt 6th gen? 

Well, looks like it's time to sell some stuff. Once these launch I'll have a good excuse to jump on board the HiFi train.