JohnW
pfm member
Bob,
The MDAC2 DD2A platform uses a Stepped attenuator on the output to avoid any form of digital domain Gain scaling, this allows Pure DSD without bit manipulation, but as a result the output impedance varies depending on level setting.
Impedance VRMS Level
Ohms
82 2.83 -6
40.5 1.42 -12
26 0.711 -18
18.6 0.356 -24
Driving power amplifier and typical 600 Ohm headphones the Output impedance is significantly low, even at the highest level settings. It depends what level you listen to with 32 Ohm headphones, maybe a buffer stage can be used but any form of extra circuitry can only reduce the sound quality - the MDAC2 design PRIMARY design goal is sound quality.
The Dual ES9038 DevDAC has a conventional output stage with digital attenuation so the output impedance is fixed "Zero" ohms.
For low impedance headphones a simple Unity Gain headphone buffer can be added - it would have to be a VERY VERY good design to avoid degrading the MDAC2 output.
The MDAC2 DD2A platform uses a Stepped attenuator on the output to avoid any form of digital domain Gain scaling, this allows Pure DSD without bit manipulation, but as a result the output impedance varies depending on level setting.
Impedance VRMS Level
Ohms
82 2.83 -6
40.5 1.42 -12
26 0.711 -18
18.6 0.356 -24
Driving power amplifier and typical 600 Ohm headphones the Output impedance is significantly low, even at the highest level settings. It depends what level you listen to with 32 Ohm headphones, maybe a buffer stage can be used but any form of extra circuitry can only reduce the sound quality - the MDAC2 design PRIMARY design goal is sound quality.
The Dual ES9038 DevDAC has a conventional output stage with digital attenuation so the output impedance is fixed "Zero" ohms.
For low impedance headphones a simple Unity Gain headphone buffer can be added - it would have to be a VERY VERY good design to avoid degrading the MDAC2 output.
and to me it looks very similar to the streamer board that is being offered here, albeit at almost half the price Pro-Ject plan to charge for their version. Most likely it was was an early development sample, the chassis looks far smarter in the Pro-Ject look to me.
