Acoustic Research M20

Acoustic Research AR-M20 Review


Some readers might find this section a little on the “lite” side after seeing other reviews that wax lyrical about how their DAPs sound with various headphones and IEMs but in my personal opinion that essentially breaks down into a series of mini-reviews of those headphones and IEMs… A DAP will have a basic signature (hopefully close to flat) that carries across to whatever you connect to it so while I will cover some pairings below, this section will be a very brief description of how I hear the M20.

The presentation is full-bodied and powerful, smooth and resolving but still remains linear and carries across all the details present in the recording. The dual crystal oscillators with their variable native sample rate tackle any kind of format with apparent ease, rhythmic precision and timing with everything from progressive psytrance to jazz instrumentals and hard rock.

As you can see in the image below the response across the frequency range is flat except for a slight dip at 4k and 6k under load. Whether this is intentional or not I can’t say but to my ears, there are no details lost as a result.

AR-M20 frequency response

Loaded test using the triple hybrid (1DD + 2BA) Moni One IEM which has an impedance of 16 ohms.

Pairing (full-sized)

Ultrasone Performance 860 32 ohms

The 680 has a linear signature and it is very resolving for a headphone in its price bracket and with the M20 I was hearing details that I hadn’t noticed before on some old tracks that I’m very familiar with. The full-bodied presentation of the M20 really makes this an outstanding match up.

Beyerdynamic DT990 Pro 250 ohm:

The swirling sub-bass in “Lost Whispers (Intro)” by Evanescence is driven along surprisingly well by the M20 and doesn’t sound lacking in any other areas either. The specified output power is 16Ω: 228 + 228mW / 32Ω: 130 + 130mW / 300Ω: 15 + 15mW and for my listening I hover around 75-90% volume with the DT990 depending on the recording and my mood. So I’d say the M20 can comfortably push 250-ohm headphones but 300 ohms (HD600) and over might be asking a bit much without additional amplification.

MSUR N650 32 ohm:

MSUR’s N650 is a warm sounding headphone so I wasn’t sure how this pairing would go. It actually surprised me because it seemed to really lift the treble and bring them to life. Listening to “Jazz at the Pawn Shop” by the Arne Domnerus Group is a real treat with this combination as they seem to have a real synergy going on with oodles of detail and realism.


From left to right – MSUR N650, Ultrasone Performance 860, Beyerdynamic DT990

M20 with Shure headphones

Pairing (IEMs)

I’m not going to cover these individually but will just state that with all of the IEMs I’ve tested with the M20 there was no evident background noise or hiss. It carried over the same characteristics as it did with the full-sized headphones – rich, resolving and full-bodied, like a glass of fine red wine.

IEMs used for testing:

  • LZ A4
  • TFZ Balance 2M
  • Campfire Audio Andromeda
  • Campfire Audio Vega
  • Thinksound ms02
  • Moni One
  • Trinity Audio Phantom Master 4
M20 with DITA IEM
M20 with Vega IEM


Battery life is listed as 16 hours and I found that to be fairly accurate, though that is 16 hours of actual playback time. I found that if listening to music for 3-4 hours per day the M20 can easily last for several days on a single charge. Turning off WiFi when you’re not streaming can eke out even more time. One of the benefits of the M20 is that there’s never really a need to actually turn off the device, you can just stop playback and let it sit as you would with a smartphone.

When you want to use it again a short press of the power button brings it to life immediately. That’s due in part to having a heavily customized Android OS running things because once a lot of those extra features and apps are removed it becomes a very energy efficient platform.

AR-M20 Comparisons

Regretfully I don’t have any other Android-based DAPs or anything else in this price range so it seems nugatory to make a comparison with my other gear at this stage. Perhaps this section will be updated at a later date.

Some extra things I would have liked (these aren’t cons as such but just things that could make the experience even better and of course it’s completely subjective):

  • Primarily a protective case, even the most basic silicone blob would suffice and at this kind of price point, it’s pretty much expected when buying something of this calibre.
  • An independent line out function for connecting to external devices (the headphone out can be used in most cases but IMO isn’t ideal)
  • Physical playback buttons so you don’t need to turn the screen on to skip/rewind etc.

AR-M20 Conclusion

There are several reasons that non-audiophile or casual listeners are content with using a smartphone for playing their music. With large, high-resolution screens, powerful processors, vibrant album art and “pretty good” sound it’s all they need.  I’ve long wished for a source with a similar GUI experience as I get on my phone for browsing and playing music added with the uncompromising audio quality of a dedicated DAP and that’s exactly what the Acoustic Research AR-M20 delivers with its Android interface and Burr-Brown DAC.

Additionally, you can connect via wireless to Bluetooth devices such as external amplifiers or headphones, browse the internet and run streaming applications. Oh, and did I mention this thing is gorgeous? The AR-M20 is a great portable device with powerful, transparent and linear presentation and the resulting sound that comes from it is nothing short of exceptional.

You can buy the AR-M20 on Amazon HERE.

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