EDIT: Please ignore these measurements. A driver issue caused noise floor to raise due to conversion to 16 bits with dither (hiding its artifacts). Updated measurements show much better results. See: https://www.audiosciencereview.com/...ac-and-headphone-amp-review.10179/post-278497

This is a review and detailed measurements of the Hegel HD12 DSD USB DAC and Headphone Amplifier. It is on kind loan from a member. The HD12 came out in 2015 and cost US $1,400. It is now discontinued.While the enclosure is the typical understated Hegel design, it seems too plain and uninteresting to me:The remote is the dirt cheap units with membrane keys. It weighs nothing and can be easily lost. Only the lower buttons work with the DAC even though one would think the filter button would be useful here.The 7-segment LED display is of course quite primitive but does the job.The back panel shows lousy attention to fit and finish:The case is literally bowed up in the middle because of some kind of foam insulation. The sharp edges of the stamped steel has no place in such an expensive DAC.For testing, I downloaded their drivers as the standard one truncated to 16 bits with ASIO4ALL wrapper interface I use.Given my preference for XLR ports on audio products, I started testing using that:I was surprised by the oddball output level of just 2.5 volts. This was at volume level of 100 so could not be increased. For grins, I also tested with RCA out and was doubly surprised that it too output the same voltage! Here it is with the volume set to 93 to get our nominal 2 volt:Is one port just wired to the other and there is no true balanced output?The SINAD of 93 dB is quite poor even for a DAC that came out in 2015. It can't even resolve 16 bit signals properly:Looking at the make up of the signal in FFT though, we see distortion products are below -110 dB so it is noise that is causing the poor SINAD/THD+N.Measuring dynamic range the standard way doesn't reveal this problem:So noise must be going up with the amplitude of signal (noise modulation).Filter behavior is classic DAC chip response:The high noise floor comes to surface in IMD distortion test relative to level:That is a massive gap relative to our reference DAC (Topping DX3 Pro).Jitter test shows strong data dependency:In other words, the digital audio samples impact what comes out of the analog output of the DAC in the form of spurious tones. Not good although audibly not a major concern.32-tone test simulating "music" shows the low distortion again:Linearity is not competitive showing lack of accuracy in reproducing small signals:I jumped right to the most important measurements which is power into 300 and 33 ohm loads:The high noise floor of the DAC immediately translates into less than stellar output. Sadly, the power is not that great either to make up for that.Output impedance is low enough:It is quite surprising to see a $1,400 DAC fall short in the area of noise. Poor jitter performance adds to that showing that the HD12 was either not designed well, or its performance not properly evaluated using measurements. Its headphone amplifier is more or less a "checklist" item that simply is not competitive in power or pure performance. Combine this with lackluster look and finish and there is no place to hang your hat on.When I look at high-end audio, I like to see over-design in the form build quality, attention to smallest electrical detail such as noise, and leaving no stone unturned to give addition performance. I see none of that visible here in Hegel HD12 DSD. 2015 is that that far back to excuse any design like this. I am very disappointed as a result. Even at very low used prices, I can't recommend the HD12 DSD. Other than the brand, it has nothing going for it.--------As always, questions, comments, corrections, etc. are welcome.You ever hear of figuring panthers tap dancing? Me neither. But that hasn't stopped the panthers from demanding tap dancing classes to improve their modelling skills. I appreciateto fund this, no matter how silly, using : https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/