My motivation on the 840c is because my Wadia 830 does not have digital outs. I now have an Aberdeen modded Tact 2.0s with A/D and D/A boards. I love the Tact, but feel that having the Wadia do a double D-A-D-A dance can't be a good thing. Given the 840c's ability to upsample to 24/192 on digital out which matches what the Tact accepts and operates at, I thought I'd give it a shot, particularly given all the hype.
Only had it for a couple days so I'm just burning it in now and haven't given it a serious listen. Out of the box, it seemed a bit edgy (to be expected on new equipment) yet had excellent dynamics and a big soundstage. But truthfully, that's based on maybe 20 minutes initial listening just to make sure it worked when it arrived. My plan is to spend a lot of time next weekend doing some critical listening. I'll be sure to post...