Mosa1Yes, these will pair well with the 6xx. However, I believe the JDS Atom + Topping D10 will be a better option. The DX3 Pro is another good option if you prefer a combo unit vs two separate units. The reason I say this is because I did read some reviews that said the internals were poorly put together. In terms of sonic qualities, the Atom does measure better than the O2 amp does (After all, it is the successor) but will that really make any noticeable difference? No, it most likely won't. As for the dac portion, both the topping d10 and the sdac perform the same.
kevinhI'm not sure what the mini is. If you go to Topping's website, there's no such thing as the D10 mini. And if you compare the chips on the Amazon website for the "mini" and the specs on Toppings website for the D10 "non-mini I guess," they literally have the same chip and specifications, and they look the same.
So maybe I'm wrong, but as far as I can tell, they are the same thing, but for some reason, some sites have it listed as "mini." That's my guess.