Officially, the best card supported for dual graphics with an A10 is the HD 6670. When the platform came out reviewers stated that HD 7700 series was incompatible. However, in the past few months reports have started to surface that DG with the HD 7700 series had in fact become possible, perhaps following a driver update.
Two users have reported success along with proof of their results here: http://www.techpowerup.com/forums/showthread.php?t=180080
The driver name is "AMD Radeon HD 7660D + 7700 Dual Graphics" and returns a few hits from a Google search, one of them from GPU-Z dated April 12th: http://www.techpowerup.com/gpuz/v8cr9/
My question is, is 7700 series now supported for dual graphics with an AMD A10, officially or unofficially? I'm wondering because I'm thinking of adding a fanless HD 7750 to my HTPC build and if it can still benefit from the APU that would be awesome.