Fostex's weak QC would result in a lot of driver pairs being inbalanced by a couple dB, but I strongly doubt that you'd see a lot of variation in the FR.

There is more to it that that Mav. An important part of a headphone is indeed the driver, and Fostex may have some QC issues that a modder would have to handle if he or she wants to insure primo performance. But then there is also construction. If you force feed a defective ADP into a measurement baffle, you can make it measure like this.



But once construction issues are taken into consideration it can measure like this (and sort of sound like so):



What you are seeing above in both cases is the same ADP BTW (NoOne's)...

Being in business selling your creative work, almost always involves two things:

1) Creating a compelling product

2) Producing it over and over again, exactly like the original, with that production done by people other than the creator(s).

The first part is far more compelling in media articles, but the second is equally significant.

Chefs like Bobby Flay have had to create systems whereby their culinary creations are presented to customers, without the chef being present. Many do an excellent job, because this is a well known part of the business.

In his Head Fi blog, Jason has described the difficulties of consistently reproducing electronic designs - which are easier to reproduce than transducers, especially modified ones.

When a craftsman can produce his own stream of products (e.g. custom guitars), you don't have these issues.  And if you are a giant multinational corporation (Sennheiser) than you full-time QC staff.  In between there be sea monsters. 

My Alpha Dogs are excellent - but I know that they were one of the early ones done by Dan personally.

I think that the best value in his products is the "Mad Dog Pro" which has the baffle from the Alphas, but use the T50RP enclosure to lower the cost.  It has a lot of the good qualities of the Alpha Dogs at a lower price, and a lower weight.

I use my Mad Dog Pro's a lot - always with the Schiit Vali (and with the HRT Music Streamer Two Plus that I used in my main system before I replaced it with Schiit.)