Not true at all. There entire line in the thousands (1000, 2000, 3000, along with 1500-9500) is still done in house with the official made in USA tag (which is hard to get).
Steel, voice coil, spiders, cone, and terminals all sourced here.
There line in the hundreds (200-700) is made overseas but it's far from "ain't worth a crap"
Redline is literally better than any mid tier china brand (American bass, Soundqubed, entry level sundown).
Chinese junk subs don't use upgraded pole venting and USA sourced voice coils. There's a reason why the redline series is expensive both new and used, it's a solid product.
DD isn't going to ruin there 20+ year reputation by giving there vendors CT Sound/Skar level quality, lets be real here