Sorry it's taken me so long to get back here. Buried at work.
Here's where I'm coming from:
First, Dan: Holy crap! These things are awesome. It's one of the very few times in life that I've gotten a product that is absolutely worth more than I paid for it. You've done a spectacular job with the Alpha Dog.
Now, the rest of the story: as I was waiting for the AD's, I came across a pair of TH600's on sale. Being the impatient sort, I picked them up. And greatly enjoyed them. They're a magnitude better than the aged DT990's (250 ohm) that I had been using both for my radio work and for general listening.
But, then, I got the AD's. And the same magnitude of difference I heard between my old phones and the TH600s, I again heard, between the TH600s and the ADs. Breathtaking. The day they came in, I'd hoped to listen for 20 minutes or so as my family watched the Olympics. 2 hours later, I wondered why everyone else was going to bed. I was just getting started! Songs that I had just rediscovered with the TH600s were again renewed, but to an even greater level. Stuff I'd been listening to for decades came alive. (I especially enjoyed my Crystal Method cuts).
With the TH600s, I tried to explain to my son about how you should be able to place instruments and voices within the soundstage (listening to Lyle Lovett's "Church"). With the AD's on the same tune, it seemed I had the perspective of the piano player! Incredible.
So, I'm happy for Fostex, selling their little T50RP's for a C-note a copy. But they're also trying to sell the TH600 for SUBSTANTIALLY more. And, quite frankly, there's absolutely no reason to buy the TH600 with the Alpha Dogs around. The TH600 does NOTHING better than the Alpha Dog, and the Alpha Dog does EVERYTHING better than the TH600, and for less. Whoever was in charge of the TH600 project at Fostex should be ashamed. All of the resources at hand, and none of the results. Job One at Fostex should be hiring Dan, at least as a consultant.
Now, my question is whether to retire the DT990's and use the TH600s as my radio monitors, or soldier on with the DT990 and sell the TH600.
Congratulations, Dan. Job well done!