is the esoteric dv50 still a good cd player?

Yes, I have heard similar comments as well. I don't know if this is the difference in the DACs or what. But I certainly cannot disagree with you. I know you have posted elsewhere the difference in the DV50 and the 840. Maybe that thread will give you more of the answers you are seeking.

the 840c is quite a bit better than the 640c as i know

In short, yes it is still a very good player. IMO, it will be better than most $2K-$2.5K CDP available now. I like Esoteric's "sound", it is more detailed than your existing player (I have a CA 640H that has the 640 CDP in it for that portion of the device). I know/hear the 840 is better than the 640, but I don't know by how much.

If you can swing for a SA50 (which I currently own) I think that would be a better move, but you are talking two times+ the money. The nice thing about the SA50 is that it has digital inputs for a server based system - which is where we are all likely to ultimately end (in addition or not, to a CDP - IMO).

I used one for years and it is a very good player especially for the price they go for now, does everything but Blu-ray and has excellent bass control and definition.

I moved up to EMMLabs and got much smoother mids and highs with the same or better bass control but it cost a lot for the jump!

is it comparable to cambridge audio 840c?

what do you mean by average?

thanks

I found it to be better then average as a cdp. I found it to be a great transport used with one of the newer dac.