While these 2 platforms hold a similar name, they actually couldn't be more different! :-)
The 2x4HD has 10x more processing power, USB audio streaming, and a lot more control features. It's the next-generation platform based on XMOS + SHARC DSP. Here is a good summary table:
miniDSP 2x4 | miniDSP 2x4HD |
|---|---|
| 28/56bit Fixed-point DSP Engine | ADSP12489 400MHz Sharc floating-point DSP |
| 24 bit ADC/DAC resolution | 24 bit ADC/DAC resolution |
| Unbalanced analog audio inputs switchable with a jumper between 0.9Vrms and 2Vrms | Unbalanced analog audio inputs switchable with a jumper between 4Vrms and 2Vrms |
| Digital I/O: I2S in/out | Digital I/O: USB audio & Toslink (44.1~192kHz), I2S I/O (not enabled yet) |
| Unbalanced analog audio outputs: Max 0.9Vrms | Unbalanced analog audio outputs: Max 2Vrms |
| Plug&Play USB driver and real-time Software configuration using miniDSP plug-ins | Plug&Play USB driver and real-time Software configuration using miniDSP plug-ins |
| N/A | Asynchronous USB Audio Class 2 Bidirectional streaming with ASIO drivers under Windows, driverless under MAC Osx |
| The device does not require a PC once configured | The device does not require a PC once configured |
| Software: miniDSP 2x4 plug-ins | Software: miniDSP 2x4 HD1 plug-in |
| Control: Volume control by a potentiometer on a 3pin header | Control: IR remote + multicolor LED for preset indication |
| USB self-powered device and wide range of DC power options (4.5 to 24VDC) | External single 12V supply (UK/EU/US/AU adaptors provided) |
| Price: 105USD | Price: 205USD |