As a Prepro and not needing the amp section I think the things that may interest you are the 805 has a better THD number .05 vs .08, the highly regarded Burr Brown DACs and THX Ultra. The 705 has Cirrus Logic DACs (no slouch either, but short on WOW factor) and THX Select. My gut reaction would be, if the power isn't an issue but the wallet is, then 705. If you can throw the bucks at it and you believe the the aforementioned specs are really worth it than 805. Honestly, you can't go wrong either way. Of course if you really need to throw bucks at it the Integra 9.8 would be an excellent option.
Some days it's hardly worth chewing through the restraints.