The M12 uses what was previously the Zetex ZXCZM800 chip, which was purchased by CSR CSRA6601, and is now part of Qualcomm.
The chip has some interesting features such as a 35 bit digital volume control and a use of PWM in its processing. There is a high degree of IMD distortions that was tested in earlier products, but it was fairly low in level so audibility didn't make it a major issue.
The Stellar DAC uses the ESS9018, which also has an IMD issue, but very typically a little lower in measured compared to the chips NAD uses.
The PS Audio DSD line is entirely different and uses FPGA chips in a similar fashion to what Chord does. Many use FPGA to implement custom controls or filtering and processing, but few use them as a complete DAC solution as you must carefully construct an analog output since the FPGA chip contains none. Some of the latest Chord designs have achieved some rather excellent performance, so its feasible to use this route to get the job done, but some of the top shelf chips out there can also get right up there as well.
One thing of note is that with FPGA based designs, it is possible to improve performance with firmware upgrades. This is something that PS Audio has successfully accomplished with the DSD over the years.
The chip has some interesting features such as a 35 bit digital volume control and a use of PWM in its processing. There is a high degree of IMD distortions that was tested in earlier products, but it was fairly low in level so audibility didn't make it a major issue.
The Stellar DAC uses the ESS9018, which also has an IMD issue, but very typically a little lower in measured compared to the chips NAD uses.
The PS Audio DSD line is entirely different and uses FPGA chips in a similar fashion to what Chord does. Many use FPGA to implement custom controls or filtering and processing, but few use them as a complete DAC solution as you must carefully construct an analog output since the FPGA chip contains none. Some of the latest Chord designs have achieved some rather excellent performance, so its feasible to use this route to get the job done, but some of the top shelf chips out there can also get right up there as well.
One thing of note is that with FPGA based designs, it is possible to improve performance with firmware upgrades. This is something that PS Audio has successfully accomplished with the DSD over the years.