What is MQA, and does it still matter?

What MQA set out to do

In the mid-2010s, streaming a true high-resolution file, 24-bit at 96 or 192 kHz, took several times the bandwidth of CD quality. MQA, developed at Meridian Audio and launched in 2014, proposed a way around that. The file would stay close to CD size, with the extra high-frequency information hidden inside it, so an ordinary player would play it at roughly CD quality and an MQA-aware one would recover more.

The name made a second claim: authentication. An MQA file was meant to confirm that what you heard was what the studio had approved, signaled by an indicator light on a certified DAC.

Its originators, Bob Stuart and Peter Craven, described the idea as one managed chain from the studio's converter to the listener's DAC, in which the sample rate and bit depth of each link could change along the way. MQA also claimed that its processing reduced the time smearing added by conventional converter filters, which it called deblurring. That claim was disputed from the start.

How the folding and unfolding work

MQA splits the audio by frequency. The content above about 24 kHz, which a 48 kHz file can't hold at its normal sample rate, is coded at reduced resolution and tucked into the lowest bits of the file, below the level of the music. MQA called this folding "origami".

Playback happens in stages. A core decoder, often software in a streaming app, performs the first unfold to 88.2 or 96 kHz. A renderer in the DAC, or a full decoder, completes it and applies MQA's own digital filters. Without any decoder you hear a roughly CD-quality stream with a little extra noise in its lowest bits, where the folded data sits. The bit depth explainer covers why those bits normally hold the quietest part of the music.

MQA-CD applies the same idea to a disc. It is an ordinary 16-bit, 44.1 kHz audio CD that plays in any CD player, with MQA data in its lowest bits, and a DAC that decodes MQA can unfold it when a transport sends it the untouched bitstream over a digital connection.

Why engineers criticized it

The main objection is that MQA is lossy. The folded band is coded at lower resolution, and bits that would carry music in a normal file carry that data instead, so the decoded result is not the original. Independent tests with signals outside MQA's assumptions about real music found output that differed from the input, which sat badly with the words "master quality". FLAC, by contrast, reproduces the original file bit for bit.

The filters drew comment too. An MQA renderer replaces the DAC's own reconstruction filter with MQA's, which are short and roll off gently, trading some aliasing and imaging for less ringing. That is a known engineering compromise, and it takes a decision away from the DAC's designer.

Licensing was the third issue. Every step, from the studio encoder to the decoder in the DAC, needed a paid license, and the indicator light confirmed that an MQA stream had arrived intact, which says nothing about whether it sounds better than the lossless original. Much of the argument was about control over the distribution chain.

Where MQA stands now

MQA Limited entered administration in April 2023, according to its record at Companies House, the UK company register, and has since been renamed Wave Realisations. Its technology passed to Lenbrook, the company behind NAD and Bluesound. Tidal, the service that carried most MQA content, moved its high-resolution tier to FLAC and finished removing MQA in 2024. The major streaming services that offer high resolution today deliver it as lossless PCM.

Does MQA support still matter on a DAC?

For most buyers, very little. If you stream from a lossless service or play your own FLAC files, MQA decoding does nothing for you. It matters only if you own MQA-encoded downloads or MQA-CDs and want them fully unfolded.

The site's DAC reviews record it either way, because it is a fact about the product. The SMSL DL100 and SMSL DO100 PRO both decode MQA and MQA-CD. The SMSL RAW-MDA1 does too, and its review calls the feature not very useful for a reviewer whose library is lossless. The Henry Audio DA 256 leaves out MQA and DSD altogether, and plays PCM up to 24-bit/192 kHz on every input.

If you want to know whether a file sold as high resolution carries real content above the CD band, the hi-res audio checker draws its spectrum in the browser. The DAC guide ranks converters by what they do with ordinary PCM, which is almost everything you'll play.