Not a bad a Dac for 2K new much cheaper on the used market. Was able to compare this Dac with 3 other dacs I have accumulated over time. The first is the Berkeley Alpha 2. The M51 eeks out as much detail but lacks the pace, timbre, soundstage size and separation Of instruments of the Berkeley. Comparing it to the Auralic Vega, the sound was much closer especially on 24/192 recordings. In the end the Vega was still more musical and created a more realistic presentation. Lastly I compared it to a 20 year old Parasound Dac 2000. Things got real interesting here. I had forgotten just exactly how good the Parasound is. In fact the Parasound not only walked all over the M51 it also, playing HDCD through it, ate the Vega’s lunch to the point that I sound the Vega. The Parasound and Berkeley are obviously from the same vein as the old UltraAnalog guys migrated to Berkeley after UA closed shop. Of the 4 dacs tested, the Berkeley was hands down the best, then the 20 year old Parasound then the Vega and finally the M51. Considering 2 of those dacs are nearly twice the price, I though the M51 fared well. The biggest surprise was the Parasound. It and the Berkeley were definitely the most musical and created the most realistic presentation in my system. The 4 dacs mentioned Classe CP-65 pre Spectral DMA 360 monoblocks Eggleston Andra III speakers Bryston BDP-2 digital player Levinson 31.5 transport. All Transparent Reference cabling

Not a bad Dac. Kind of sterile and forward much like the old Krell SBX and Studio dacs. Really lacks rhythm, pace and somewhat of a compressed soundstage. Timbre and decay of instruments are fairly good but there seems to be a slight smearing or rounded off of their placement within the soundstage. This might work well with a good tube pre or tube amp.

I genuinely wanted to love this DAC based on rave reviews. What I got instead was a DAC that sounded dull and veiled. I ended up getting a Stello U3 USB to SPDIF convertor just to try to make the DAC sound in any way interesting in my setup. In the end I gave up. This thing was lethargic and lifeless to me. I gave it a good go and spent extra improving cables and buying the Stello but still found it un-listenable. Sold it at a loss.What a shame it didn't sound as good as it looked!

This DAC sounds amazing. This is my 3rd DAC (Peachtree Dacit, Woo Audio WDS1) and it really stands out from my previous DAC's. This DAC has presence. There is a huge sound stage, with great definition of instrument location, however it does show up poor source material as being just that. Feed it the right material and this DAC shines a very bright light. I love listening to this DAC, it is very easy to listen to over prolonged periods. i run it through a Rotel power amp and it just sounds sooooo, good.

Nad M51 sounds like hifi. As opposed to real music, as opposed to natural. Incompatibility with my amplifier maybe, but I sure do not like. The differences between firmware are huge. The latest one sound the most hifi.