This is a review and detailed measurements of SMSL M10 desktop DAC and headphone amplifier. It is on kind loan from a member. This is a "high-end" unit from SMSL and retails for USD $545 from Amazon including free Prime shipping.As soon as you take out the M10 out of the box, you definitely get the feeling that this is one hefty unit. It is not as heavy as SMSL D-1 but it is up there with inclusion of a power supply and such. The display is also much larger than more budget oriented SMSL DACs and amps:As you can see, the SMSL M10 sports both 1/4 inch headphone jack and XLR for "balanced" headphone output. You would need to select either one of these in the menu in addition to whether the headphone output is on or line out.For output, we have both RCA and balanced XLR outputs which is really nice and expected in this price range.Menus are pretty intuitive to follow with push of the power button and rotary knob. The display supports a set of colors including white (above), green, red, etc. Wish it had used the colors within the same display to distinguish things but that likely takes up more RAM than the little microprocessor has.For my testing I focused on USB input. Since there are both types of output, I focused both. Let's get into the measurements and see how she did.Let's start with measuring the DAC portion alone first using RCA/unbalanced outputs:This is not a good way to start the show. SINAD (signal over distortion and noise) is just 94 dB. THD+N which is the same metric stated as a percentage, seriously underperforms the stated number (0.0019% versus 0.0004%) by a factor of five! Output is a bit hotter than we need so I dialed it down and it unfortunately did not improve the distortion metrics. Neither did switching to balanced output:Those second and third harmonics are way too high for this class device.As an aside, notice how the mains spikes to the left of our 1 kHz signal in RCA output are completely gone in balanced mode. This is why I always suggest getting balanced interconnects between DACs and amps. It nicely eliminates mains/power supply related currents which are the cause of nasty ground loops.Here is how the distortion rates among other DACs tested:Not a good place to be for sure seeing there are much higher performing DACs that cost less.Dynamic range for both outputs is decent with the balanced taking the lead:Here is the intermodulation distortion test:Balanced output (pink) is slightly less noisy than RCA (green). Both outputs saturate some at higher levels, causing them to underperform the much cheaper Topping DX3 Pro (dashed red).For those of you who are fans of our 32-tone test signal, here is how the SMSL M10 performs with RCA outs:We see an odd thing for the first time where the bottoms of each valley (noise floor) goes up and down. We call this "noise modulation" meaning the fact that there is a signal there in that frequency, causes the noise floor to go up.The problem is not there with balanced outputs:Then again that is a pretty busy graph there showing more distortion products in between the tones as our dashboard predicted.Jitter/spurious response is not perfect but very good nevertheless (ideal graph has only one spike at 12 kHz):It is not all bad news: SMSL M10 nails the linearity test:Let's switch to measuring the headphone output with 300 ohm load:Boy, this is quite disappointing. We not only lack sufficient power but also suffer from much higher noise floor than our reference Topping DX3 Pro.XLR headphone out has more power but still very much non-competitive:Power output is well under the spec prior to severe clipping.Worst news here is the very high output impedance of 24 ohms for 1/4 inch output:The SMSL M10 starts with a good out of box impression with hefty chassis and decent design. Sadly the moment you put it on the bench, the results are very disappointing and non-competitive on both DAC and headphone amplifier. You could argue that distortion differences between DACs are hard to hear but amplifier power is very important and SMSL M10 is very deficient in that front. As such, I cannot recommend the SMSL M10 for purchase. If I were to give a letter score, it would be a "C."-------------As always, questions, comments, recommendations, etc. are welcome.Can you imagine how much fun it would be for me to go to UK and harass Thomas? Please considermoney so I can fly there using: https://www.patreon.com/audiosciencereview ), or https://audiosciencereview.com/foru...eview-and-measurements.2164/page-3#post-59054 ).