Check out this thread and @Resolve’s review:
Drop sometimes creates custom products, sometimes offers substantial discounts, and sometimes is just another retailer. They have regular sales as well. They generally name all the “unique offerings” with an “X” somewhere. This started with the Sennheiser HD 6XX, which is often described as guts of the HD 650 with midnight blue plastic parts and a much lower price tag.
Per my observations and discussion in the thread above, the DCA at Drop are likely AEON Flow generation 1 models (NOT gen 2 as available from DCA) with new pads/tuning and an X in the name.