From the press release (apparently not yet on the SD site):
Introducing the 664 Field Production Mixer
Sound Devices introduces the 664 Field Production Mixer, the newest addition to Sound Devices mixer line. The flagship 664 builds on the features of the popular 552 Production Mixer and offers expanded input/output connectivity, additional recording capabilities, and full-featured time code. See the 664 on display at IBC, stand 8.D74.
Key 664 features include:•Six high-bandwidth, low noise microphone preamplifiers with phantom, limiters, high-pass, pan, and direct outputs per channel
•Four output buses, Left, Right and Aux 1, Aux 2; transformer-balanced for freedom from ground loops; multiple output connectors, including dual multi-pins
•Built-in production recorder, records all inputs and output buses, 10 tracks. With CL-6 Input Expander, records 16 tracks.
•Broadcast WAV recording to dual memory card slots, CF and SD Record, with different track combinations to each card type
•Ultra-accurate, Ambient Lockit-based time code generator/reader with auto-recharging of internal TC battery and time code compare tool
•Sunlight viewable, transflective LCD menu
•Two AES42/AES3 digital inputs (input connectors 1 and 6) and AES3 output selection, up to eight channels of AES out (XLR, multi-pin)
•Expanded return monitoring capabilities, with three camera returns and dedicated communication circuit (PL)
•Built-in slate microphone and external slate microphone input connector