The C-Media chip is the limitation for 176.4, not the AKM. SPDIF does 176.4 just fine.
And yes, there is a new USB input board coming in a couple of weeks, to solve the handful of remaining "screeching" problems (literally like 30 out of 3000.) Contact us (or your distributor) if you need a board.
Only 3000? People need to buy more! :-)