what is the difference between Cary 805b vs 805c

Can someone tell me the different between a cary audio cad-805b vs a cad-805c?

The 805 series has been in production for a number of years. While there are some internal changes in the 805C over the 805B, the biggest difference is the output tube. The B uses a 211 and the C a 845. They both use the same input and driver tubes. I had the 805B in my system for a number of years with NOS tubes, I auditioned the 805C in my system for 2 weeks and found the differences subtle at best and decided to stay with the B. Go to the Cary Audio website and look at the review section, there is more information there. Good luck.
One thing you should keep in mind bewteen the B and C versions is what that difference in output tube means.

The 805 - I own the B with a switch to let me also use an 845 output - sounds mushy with the stock Chinese 211 or 845. To have the amp sound good you really need NOS tubes; in the case of the B, GE211's are fine (@$220 matched pair) and sound MUCH better (I have RCA 211's but they are quite hard to find; the GE's were nice too and are relatively easy to find). BUT, the C version, to NOS retube the outputs, requires an RCA 845 tube and that is going to set you back $600 pr, assuming you can find a matched pair! So, if you get a C, you are stuck with the stock 845's, while with the B you have more latitude to increase your amps performance (a B version with GE211's blows away a stock C version IMHO).

One thing to check when looking at 805's is to remember that the B version came stock with Cetron 300B driver tubes - which you really must replace with WE300B's to hear what the amp is remotely capable of (on used market new production WE's are $495 matched pair from a dealer unloading stock). The C version comes stock with WE's. Try to find an 805B where someone has already replaced the drivers with WE's (they have 40K hr tube life so no worries there).

Good luck!