I am the original owner of this excellent, well reviewed DAC from the NAD Masters Series. I purchased it in 2012 and listened to it virtually every day up until about a year ago when I splurged and bought an MSB DAC ($$$$$). Lots of information and strong reviews about the M51 are readily available online. The 8/10 rating is conservative. The only imperfection is a small scratch on the top, near the back, which is visible in the photos. Truly beautiful sounding.