Never owned the 840C, but have compared the two side by side on my dads system. They’re definitely different from each other and I can see how some may prefer the older unit. To start with the casework on 851C is hands down a better box. Some feel the 840C is warmer and I think at first it does sound that way but the truth is the 851C is so much more revealing, has more air and more extended on top and bottom.
When we listened to the 840C it sounded very similar to my dads CA DAC Magic. The 840C might have been a smidge better but it wasn’t by much. Still a nice player.
I love my 851C and I will tell you it really shines with great cables. At first I used Clear Day Cables Balanced IC with a Kimber PK10 Gold PC and that worked well, but switching over to WyWires Silver Juice II PC and Silver Balanced IC has taken it to another level. I also switched out the two fuses to SR Blacks which really opened things up.
In my opinion the 851C is hands down the better machine, but if you do not have or will spend the money for nice cables you may not hear much of a difference. The 840C is still a very nice machine.
When we listened to the 840C it sounded very similar to my dads CA DAC Magic. The 840C might have been a smidge better but it wasn’t by much. Still a nice player.
I love my 851C and I will tell you it really shines with great cables. At first I used Clear Day Cables Balanced IC with a Kimber PK10 Gold PC and that worked well, but switching over to WyWires Silver Juice II PC and Silver Balanced IC has taken it to another level. I also switched out the two fuses to SR Blacks which really opened things up.
In my opinion the 851C is hands down the better machine, but if you do not have or will spend the money for nice cables you may not hear much of a difference. The 840C is still a very nice machine.