This is a review and detailed measurements of the Audio-gd DAC19 DAC. It is on kind loan from a member who sent me two of their DACs for review. The DAC19 costs US $640 plus shipping from the company's website.The design of DAC19 is similar to the rest of the Audio-gd line:Controls feel solid and good. The unit also has good bit of heft to it so overall impressions are positive from a male perspective.The back panel is what you expect plus a couple of their current-driven proprietary "ACSS" connectors:At this price range, XLR balanced output should be mandatory to help avoid ground loops which can readily occur with computer audio. It is missing here which is disappointing.There have been many revisions of this model over the years. I think the original unit came out in 2010 and seems like that is the marking that is on the back of the unit. I am not an expert in all of that so don't know where this unit ranks so I took a picture of the inside:It doesn't look like their current units that have an FPGA based daughter card. The analog design and choice of DAC chip (PCM1704 ?) seems the same though.There are some jumpers on this unit but I could not correlate them to anything on the Audio-gd website so went with them as is.Prior Audio-gd products have not done well in my testing. They tend to get poor measurements and miss the published specifications. Will the DAC19 be an exception? Let's find out.Firing up the DAC19 with full amplitude digital signal of 0 dBFS as I start testing showed an output that was above nominal 2.0 volt we like to see (not a bad thing). So I dialed it down digitally to get us to 2 volts which improved the results a bit:That second harmonic at almost -80 dB sets the SINAD for the bad channel at 80 dB. The other channel is 8 dB better showing lack of precision in design. Averaging the two channels gets us a SINAD of 84 dB which is best I have measured for Audio-gd (I think) still puts the DAC19 in forth bucket of all DACs tested:There are no specifications for THD+N on Audgio-gd website for DAC19 but there is one for SNR so let's measure that:We are missing the specifications by almost 17 dB! Still, we clear the bar for CD/16-bit music so it is not the end of the world.Jitter performance shows poor attention to clean engineering:I lowered the output to -60 dB and most of the spurious tones disappeared (in red). Since real music doesn't have such high amplitude at 12 kHz, actual performance there may be OK.Linearity measurement is a disaster:The oscillating up and down usually indicates predictable error in signal processing/dithering. I changed the levels manually from -110 up and nothing would change in the output until I got into the 90s dB. So something is broken here. The error now goes well into CD territory as we can't get correct output level to -96 dB.Intermodulation distortion test shows high noise and distortion levels as predicted by the dashboard:I could not run my multitone test because it is 192 kHz sampling rate and even over USB, I could not get the DAC19 to recognize that. It is beyond the specs for the device (96 kHz).The reconstruction filter shows a very slow roll off:Even by 24 kHz, we only get 40 dB of reduction of out of band components. Ideally this number would be far, far bigger. At 22.05 kHz, we are only down a negligible 6 dB (theory mandates infinite truncation at this point).The slow roll off also bleeds into audible band:We have lost 1.5 dB by 20 khz which is not an issue for us older folks but for younger listeners, there will be somewhat less highs. Maybe this is the appeal of this DAC for some?The data clearly speaks for itself: the performance of the Audio-gd DAC19 under test is not competitive at all. At the price charged, it both lacks features such as balanced output and pure performance. The newer revisions may have made the jitter and roll off issues less of a problem but I suspect the rest remains due to avoidance of feedback and good design practices.It is a shame really. Looking inside, the DAC19 warms the cockles of this engineer's heart with old school use of tons and tons of discrete parts. A lot of work has gone into the design of this unit, yet with no aim to verify good performance.From audibility point of view, the distortion levels are low enough that the average audiophile won't hear. No, there is no magic that they will hear either to make this design superior.Needless to say,There are so many better choices today at far lower prices.------------As always, questions, comments, recommendations, etc. are welcome.I am going to get a haircut today. One of my pink panthers heard me saying that and says he too wants a haircut. Problem is, I can't afford a panther haircut. They have to be tranquilized and such so it costs a lot more than human haircuts. I feel bad for him so please donate some money so I can give him the grooming he deserves using:: https://www.patreon.com/audiosciencereview ), or https://audiosciencereview.com/foru...eview-and-measurements.2164/page-3#post-59054 ).