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Last June, Jim Austin briefly discussed the operation of MQA in his review of the Meridian Explorer² USB DAC, but you can find a more detailed explanation on Stereophile's website here and here. MQA involves two fundamental concepts, discussed in a paper presented to the Audio Engineering Society in October 2014. The first is responsible for a large reduction in the bandwidth required to store and stream high-resolution files, the second for a potential improvement in sound quality. . .

A freelance reviewer's workload is erratic. On the odd occasion one might have a few moments' respite, while at other times the coincidence of multiple deadlines for copy results in several weeks of panic. As I write this missive I have just completed one such overload period covering so much equipment that I thought that it would be worthwhile to look back and take stock at the audio in the past decade (footnote 1).

Our meeting was propitious and totally unexpected. The locus was Los Angeles' Sheraton Gateway Hotel last May, on which we had all descended for Home Entertainment 2006. As a contributor to Stereophile's Show">http://blog.stereophile.com/he2006">Show blog, my assignment was as liberal as they come: Go where you are drawn, listen as you will, and record your impressions.

This series of articles is based on a paper presented at the 103rd Audio Engineering Society Convention, New York, September 1997. The preprint, "Loudspeakers: What Measurements Can Tell Us—And What They Can't Tell Us!," AES Preprint 4608, is available from the AES, 60 East 42nd Street, Room 2520, New York, NY 10165-0075. The AES internet site, www.aes.orghttp://www.aes.org">www.aes.org;, offers a secure transaction page for credit-card orders.

This series of articles was initially written (in slightly different form), as a paper presented at the 103rd Audio Engineering Society Convention, New York, September 1997. The preprint, "Loudspeakers: What Measurements Can Tell Us—And What They Can't Tell Us!," AES Preprint 4608, is available from the AES, 60 East 42nd Street, Room 2520, New York, NY 10165-0075. The AES internet site, www.aes.orghttp://www.aes.org">www.aes.org; , offers a secure transaction page for credit-card orders.

The most notable aspect of Benchmark Media Systems' DAC3 HGC ($2195), which I favorably reviewed in the November 2017 Stereophile (footnote 1), is its low noise floor. John Atkinson's measurements corroborated Benchmark's claim that the DAC3 is capable of "at least" 21-bit performance. While significantly less than the theoretical potential of a 24-bit data format, 21 bits is still the state of the art, and corresponds to a dynamic range—the ratio of the highest achievable digital-domain volume to the DAC's internal noise—of 128dB. That's well above the dynamic range that most power amplifiers can achieve. A good-measuring high-end solid-state amplifier is likely to have a dynamic range—the highest attainable ratio of signal to noise—of about 100dB ref. its maximum power.

I figured it was coming, but it wasn't until just after I'd returned from the Audio Engineering Society's 2016 International Conference on Headphone Technology—held last August in Aalborg, Denmark—and was writing up my report and summary on the event for InnerFidelity.com (footnote 1) that I knew for sure: Headphones are about to change . . . a lot.