I too was curious about a Denafrips DDC almost a year ago. I would like to share my experience for what it's worth. About a year ago, I briefly owned a Denafrips Hermes DDC (Gais's little brother) and a Terminator Plus DAC. The Plus provided two clock signals to the Hermes via two $26 clock cables and the Hermes provided an I2S signal to the Plus via an $80 HDMI cable. Upstream of the Hermes, I had my USB chain at the time which consisted of the opticalRendu, Uptone ISO Regen, and Innuous Phoenix USB. The oR and ISO Regen had a DC power solution better than Farad Super3 power supplies with upgraded cables. The USB chain was finished off with the excellent Shunyata Alpha USB cable. Side note: someone mentioned The Cable Company's lending library above and I used that service to demo the Alpha USB cable about 2 years ago. It's a service I like to use now and then.
At the time, I also owned a Benchmark DAC3 B. For both the Terminator Plus and the DAC3, I preferred the full USB chain without the Hermes clocked by the Plus. I mentioned the cost of the clock and HDMI cables above because I believe they were weak links in the comparison especially when going up against the Shunyata Alpha USB cable which is now retailing for $1500. So this is the tricky part with trying to compare any DAC's USB input to say the same DAC's AES input. The digital cable and everything else up the chain from it matter so it's not even close to being an apples to apples comparison. I also ended up preferring the music from the DAC3 over the Plus. Knowing I was going to sell the Denafrips gear and get some funds, I ordered a new streamer to see if it could beat my USB chain. That's how I arrived to my current streamer the Grimm MU1. And based on my experience with Shunyata digital cables I didn't fool around and bought their top of the line Shunyata Omega AES cable. This streamer and cable is now what I use on the 005 and the Benchmark DAC3 DX.
Regarding DAC pricing, I preferred the $2000 DAC to the $6000 DAC so it's not hard for me to believe a $3000 DAC can be better than a much higher priced DAC. After comparing the DAC3 to the Plus, I thought I had to go the Tambaqui level to get a really good improvement but I'm very happy to say the 005 has given me what I wanted at a much lower price point. This last weekend was one of my best listening sessions ever with the Sennheiser IE900 and Benchmark HPA4.
I would like to thank yyzsantabarbara for helping me find the 005. I found his experience wit the Benchmark DAC3 mirrored my experience exactly down to selling it at one point and rebuying it. So naturally when he upgraded to the 005, I knew I had to try. Great decision!