I see some ZD owners use a PS Audio PWD Dac with their amp, others have a NAD M51. I currently use a Violectric V800. For those who have paired their ZDSE with either the PWD or M51, two questions:
1. what change in the sound might I experience with either of those compared to the V800?
2. knowing that the V800 / PWD or M51 comparison may not occurred, what sound quality led you to PWD or M51 for the ZD?
-AB
I'll go with 2, since I never got to hear a V800.
The M51 is a darn good DAC
for its price. For that kind of money, you'll be hard-pressed to find a better sounding DAC out there. It also has a tad warmer than neutral sonic balance, which is great when used with headphones like the HD800 or HE-6 (I don't use my ZDSE to drive the HE-6, of course, but it's one of my favorite headphones in the house).
I also used to own the Mytek Stereo192-DSD, which has been very favorably reviewed by various sources. It is indeed a solid performer, and quite versatile as a DAC/headphone amp/preamp. However, although the M51 has a digital preamp, its functionality as a DAC/digital preamp surpassed that of Mytek Stereo192-DSD as a DAC/analog preamp. And comparing PCM DAC functionality only, the M51 was a clear winner. One may prefer the Mytek if he wants to enjoy DSD recordings, or if he wants a one-in-a-box solution that has everything including a built-in headphone amp; but if your priority is purely DAC performance, then the M51 is a better option.
Actually, I kinda jumped for the M51 when it was on a big sale. After comparing it with the Mytek, I knew the latter had to go. Besides, the Mytek was priced much higher in my country for some reason, costing well over $2,000, so there was really no reason for me to keep it.
A word of advice is that the M51 performs better when using its AES/EBU input. I'm not saying that the USB input is bad by any means, but there is clearly an improvement when AES/EBU is used, especially with hi-rez stuff. I recommend using an USB transceiver like the Stello U3 or SOtM dX-USB HD to take advantage of AES/EBU. With the Mytek, I couldn't hear much difference between USB, FireWire and AES/EBU, and most USB transceivers are not compatible with DSD so there was that.
Lastly, take it with a grain of salt or two, but M51 got the highest A+ ranking on Stereophile's 2013 Recommended Components, beating several DAC's costing much more.