The Dual is for stereo or something I think. it is the way the chips are aligned. As the components are single channel components. I may be wrong. I remember it is mentioned somewhere either on hte website or in this thread.
The tube upgrade that comes with the D1 is good and defintely a good entry "upgrade" tube!.
The 396A is REALLY lovely. Deep, open sound stage. Gives the lower frequency a warm, upped feel. Punchy but not boomy.
Paired with the SUN HDAM it becomes clearer and the extension of the soundstage is opened up a little bit more ontop of that.
I run my D1 to my stereo amp and the sound is gorgeous. The same goes with headphones (obviously pending the headphones). Close your eyes and the music rises and fills with presence.
There are a few combinations here on the thread that you can dig out via eBay and play around with. :).
I left my case off as it is a bit of a hassel try to get it on and off haha. Might do a clear cover though.
You're most welcome!. I really enjoy the D1 and want to keep this thread going!