This is a review and detailed measurements of the SMSL M500 Balanced DAC and integrated headphone amplifier. It was kindly sent to me by the company although a number of members had offered the same. The M500 costs US $399 on Amazon including free shipping.The M500 takes on the form of rectangular cube which I kind of like here:The display font as well as the one in the manual are quite tiny. Fortunately when you change the volume, it switches to larger font in the center which I appreciated.The volume control feels good if a bit small.The back panel shows the good stuff as far as inclusion of XLR output:The figure 8 power cable is not as optimal as an IEC connector but does make for a lighter weight cord.After about an hour of use the enclosure was barely above room temperature so no issues there. Usage on Windows 10 was plug and play as is thankfully common.The same generic remote control that ships from Chinese hifi companies comes with this unit. Be sure to press "C" to activate it. The Fn key toggles between line out and headphone out.I was asked about MQA decoding. I found it work excellently, matching what my Roon player was reporting. By default Roon was allowing it to both decode and render MQA which is the way it should be. I hunted for 192 kHz MQA content and found this on Tidal from one of my favorite signals, James Taylor:The display on M500 showed the correct setting:Translating for others who don't follow MQA, the backwards compatible in the clear format is 48 kHz. The hidden bits allow the DAC to decode this back up to 192 kHz sampling.As a side note and a nice touch, any time you play something with > 44.1 kHz sample rate, the display shows the "High-Res" logo which in its gold coloring, looks good.So really, other than tiny fonts on the display, there is not much to complain about and a lot to like on the M500.As usual let's separate out the DAC performance from headphone amplifier and see what we have:I was pleasantly surprised to see a high output of nearly 7 volts at max volume. For fairness to other DACs measured, I cut the output down to 4.3 volt. Our worst case distortion product is below -120 dB, assuring complete transparency as that is well below our threshold of hearing. Same is true of SINAD which sums in the noise with it and still lands in truly inaudible distortion+noise.No wonder then that the M500 ranks way up in our DAC ratings based on SINAD:RCA performance is almost as good:Dynamic range (measured using AES-17 standard) is superb even with the volume turned down to 4.3 volts:Intermodulation distortion relative to input level was excellent as well:Jitter performance is extremely good:The few bits show up due to very low noise floor.Linearity was perfection in a graph with either output:You can expect our 32-tone test to also show up well and it did:Here is our usual filter responses:Attenuation was extremely good with some of these, necessitating me lowering the limit in the graph to see the floor! You have a choice of no less than three filters that truncate well by the required 22.05 kHz bandwidth of 44.1 kHz sampled audio.Finally, THD+N versus frequency shows one clean DAC when it comes to ultrasonic spectrum of noise and distortion:Let's change our connection to headphone amplifier (while driving the unit digitally) and see what we have. Let's start with signal to noise ratio:We lose good bit of our performance through the headphone amplifier. The low output of 50 millivolt which aims to measure the noise level for sensitive IEMs is a bit above average:Hopefully that lowers the probability of hissing with those transducers.Let's get into most important measurements which is noise and distortion relative to power starting with 300 ohm:We have very good noise and distortion relative to our reference, the Topping DX3 Pro. Alas, we fall short of its output power though, stopping at 63 milliwatts. I like to see 100 milliwatts or more to make it more future proof in case you use higher impedance headphones.Here is the same for 33 ohm:Now we match the Topping so we are in better shape, especially given the low noise and distortion.I started my testing with Drop's Ether CX Mr. Speakers headphones. Here, I had plenty of volume but could stand playing at max volume. It was loud to be sure but I like to see more headroom than I had. That aside, performance was very good and clean to max volume as the measurements above show (i.e. lack of clipping).I had a bit less headroom with Sennheiser HD-650 with less ability for "skull resonance" than I like to see.Fidelity otherwise was excellent though. To wit, I am still listening to the M500 using the HD-650 as I type this. Typically a good sign that I like what I am hearing.SMSL packs just about every desired feature into a DAC and headphone amplifier including MQA decoding with great measured and subjective performance. The only weakness is that its amplifier doesn't blow your ear drums.On the performance front, it is heart warming to see companies like SMSL continuing to refine the performance of their product, lowering noise and distortion in every way they can. We have seen this progress in just a year or so. All of this comes with no premium to us as consumers. And give us products that can be proven to be transparent to the source music. You hear what was given to you by the talent and production/mastering engineers with no molestation of said bits. Puts a smile on my face from just typing these words!Given the features, performance and low price,--------As always, questions, comments, corrections, etc. are welcome.With the cooling weather, I am thinking of going to the bay and digging up some clams. That part is free. What is not is the wine and spices we need to steam them. 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