So, I edited the first post in this thread to include my listening experience which I posted later on page 2 but never copied into the first post sound quality section where I had said to "watch this space". So now that's fixed. I ended up splitting this into Sound Quality - Initial Impressions and Sound Quality - Later Impressions.
I've seen the C5D mentioned here and there online, and always in a very positive way. Seems it's well received, which is just.
Looking back on it now, I would say that I've decided, from my experience with the C5D, that when I'm doing portable, I want only headphones and a DAP (my iPhone typically, but I'm open to acquiring other DAP's in the coming years). That's it. Adding even something as small as the C5D is an annoyance that, for me, just isn't worth it. I'd rather just find headphones that pair well with whatever DAP I'm using.
For serious listening, though, I'm at home, sitting in one place, and I'm good with my laptop, my Apogee Duet as DAC, and an amp (or Apogee Duet as amp also), and headphones. Right now I don't have a separate headphone amp, but I'll probably be getting one soon. Maybe a LitteDot, maybe a Schiit. I'd definitely like to experience tubes, and rolling them seems like just too much fun not to try out at least once in your life! LOL!
But if you need portability, power, great price to performance ratio, and sheer class and quality and great customer service, then the C5D may definitely be for you. And man does that little red number look great!
OK. Thanks for reading. Just wanted to update things and bump this to the top in case anyone is thinking of the C5D.