Looks like the NUX guys are using this chip. Pretty interesting set of features for one low powered chip.
http://www.actions-semi.com/en/productview.aspx?id=195
System
• 104MHz MIPS32 M4K processor Core
• 180MHz Gogir DSP core
• Built-in 279.5K RAM for data and program storage
• Support SD/MMC/eMMC card interface and SPI NorFlash interface
• Support 26MHz OSC with on-chip PLL
• Energy saving with dynamic power management, supporting Li-on only
• USB 2.0 device and host controllers with HOST support
• A variety of serial controllers supporting I2S, SPDIF TX, SPI, UART, PCM
• Support Remote Control with the internal IRC for decoding
• Support 4COM/5COM/6COM Segment LCD, 7pin LED
• 4 LED drivers with PWM flasher independent of MCU
Audio
• Build in stereo 24bit input sigma-delta DAC, SNR>95dB, SNR (A-WEIGHTING)>98dB,THD<-85dB
• DAC supports sample rate 8k/12k/11.025k/16k/22.05k/24k/32k/44.1/48kHz
• Build in stereo 20mW PA (Power Amplifier) for headphone. PA output supports traditional mode and direct drive mode(for earphone)
• Support differential audio output for speaker PA
• Build in stereo 24bit input sigma-delta ADC, SNR>90dB, SNR(A-WEIGHTING)>93dB,THD<-82dB. With multi-bit quantization option,SNR>93dB,SNR(A-WEIGHTING)>96dB
• ADC supports sample rate 8k/12k/11.025k/16k/22.05k/24k/32k/44.1/48kHz
• Supports stereo single-ended input analog microphones or mono full difference input microphone
• Supports Digital microphones and Analog microphones
Bluetooth Controller • Support Bluetooth V5.0
• Compatible with Bluetooth V2.1 and V3.0 systems
• Supports Bluetooth 4.0 Low Energy(BLE)
• Supports all packet types in basic rate and enhanced data rate
• Supports SCO/Esco link
• Supports 4 piconets in a scatternet
• Supports Secure Simple Pairing
• Supports Low Power Mode (Sniff/Sniff Sub-rating/Hold/Park)
• Bluetooth 5.0 Dual Mode support: Simultaneous LE and BR/EDR
• Supports multiple Low Energy states
• Fast AGC control to improve receiving dynamic range
• Supports AFH to dynamically detect channel quality to improve transmission quality
• Integrated internal Class1, Class2, and Class 3 PA
• Supports Power Control/Enhanced Power Control
• Integrated 32K oscillator for power managementC
• Operating voltage: I/O 3.1V, Core 1.2V
Power • Supports Li-Ion battery and 5V power supply
• Integrate Linear battery charger
• Integrated DC-DC buck converters, which can be switch to LDO mode
• Linear regulators output VCC, BTVCC, SVCC, RTCVDD from DC5V
• Linear regulators outputs AVCC from VCC, and VDD from VD15
• Capacitor-less LDO: UVDD,EFUSE25, AVDD, OSCVDD and BTVDD
• Internal bandgap generates VREF form SVCC
• Operating voltage: I/O 3.1V, Core 1.2V
Package • QFN-68 (8x8mm2)
Application • Stereo headsets and headphones
• Portable stereo speakers and speakerphones
• Bluetooth car audio unit
• Bluetooth smart LED
• Soundbar
Wish they had some info online about the instruction set, or tools, or a dev board, or something!