You picked a great source to order blindly, most folks are very impressed by the 840C.
I absolutely adore mine, its "the" source for me, price wise and SQ-wise.
The absolute best part of the 840C is its a mid-fi source
that finally gets the highs right! I never thought I'd hear at source in this price range with highs I'd described as beautiful, but they are. The mids are wonderful as well, cool and neutral but very liquid (the 840C mids remind me of the HP2 mids, if you've heard that can).
The two places we can criticize the 840C on, albeit they are mild criticisms, are the bass and the soundstage. The bass is good, not excellent. The soundstage is medium sized as opposed to super sized. I describe it as intimate. Don't get me wrong, there is plenty of air around the instruments, imaging is great, resolution is high, its just all in a smaller space then some folks would prefer.
Neither of these criticisms affect my enjoyment of the player. I hope you enjoy yours as well!