Sony HAP-Z1ES or NAD M51?


I have squeezebox touch feeding a benchmark DAC1 to Nait-5i to Harbeth C7.

Have the upgrade fever and looking to upgrade DAC.

Hearing good things about the Sony device. Any recommendations between the Sony and NAD purely from a sound quality perspective?

Thanks!
rmata
Davehg, I found that transferring wav files to the HAPZ1 was problematic to say the least. On the other hand, AIFF, flac, ALAC etc. transferred flawlessly. I found in a few cases the wave files sounded best, but this was 2 albums of many. Most of the time, I could hear no difference between wav and AIFF.

The ability to convert redbook on the fly to dsd is huge. In a few cases, especially with older recordings, the HAPZ1 renders music that was unlistenable through my very good ModWright Sony 5400 player as very satisfying recordings.

There are a number of people who rightly have been put off by the Vtuner not working since Sept 6. If that is not an issue for you, this really is an attractive option at the price. If you can borrow one, by all means, that is the way to go.
Thanks Brownsfan. Now I just have to locate a local dealer.

Last night I received a Sophia Princess rectifier tube for the Woo Audio 6se headphone amp. It was a revelation, easily the most impressive upgrade I've done with this amp (including cables and power cords). I have to say that running with the Squeezebox/Tri-Vista setup, things were sounding just great. I also was able to control it with a nifty app on my phone.

So I'd have to demo one against my current setup to justify that it really surpasses what I have now.
A month in ... and must say the HAP-Z1ES is sounding better every day. Very smooth sound with great detail/highs and massive soundstage. Loving it. Awesome job by Sony...