Last month I wrote about Amazon's issues with streaming lossless audio (link). The company advertises high definition, yet doesn't offer lossless CD or HD audio. At the encouragement of a few Audiophile Style readers, I obtained a Bluesound Node 2i for testing. The Node 2i enabled me to test streaming from Amazon without using any of Amazon's applications for Windows, macOS, or iOS. The audio routs from Amazon's servers, through the Bluesound Node 2i's coaxial digital output and into my DAC. I could've use analog outputs in the Node 2i, but for the sake of testing the digital outputs were required. Below are my testing methodology and my findings.
I use a Berkeley Audio Design Alpha DAC Reference Series 3 that identifies and decodes HDCD on all sample rates. When an unaltered HDCD file is played, the HDCD indicator on the DAC is illuminated. The HDCD flag is on the 16 bit for CD files and the 24th bit for high resolution files. Any alteration, DSP, volume leveling, etc... changes this least significant bit and won't enable the HDCD indicator to illuminate. That's the hardware piece.
With respect to source files, here's what I do.
I have a list of roughly ten known HDCD albums (although I could use more if needed). Many of these albums were only released as HDCD encoded CDs/files. There is no alternate lossless version. For example, Reference Recordings only releases music that's HDCD encoded.
I set a baseline by playing my own local copy of the albums and make sure the HDCD indicator illuminates.
I used the Bluesound applications on iOS and macOS for playback during this test. Outside of the Amazon native apps, that I tested previously, the Bluesound app/ecosystem is one of the only systems to integrate Amazon Music HD and stream content up through 24/192.
Through the Bluesound app and Node 2i combination, I streamed my known HDCD releases first through Qobuz, then through Tidal, and finally through Amazon Music HD. I wanted to use my local file baseline, then two streaming service baselines, before testing Amazon.
Absolutely there are possible holes in my methodology, but I believe I've minimized them as much as possible. The two major ones are source material. Sure Amazon could have different source material from all other lossless streaming services, but after checking with labels, I highly doubt this is the case. The second one is Amazon's adaptive bit rate. Amazon could be sending me lossy versions of the files and sending other people lossless versions, but I think this is highly unlikely as well. I have a 1 gigabit upload/download unmetered fiber internet connection. I routinely check the speed and see between 800 Mbps and 940 Mbps. If Amazon doesn't think this is a fast enough connection for lossless audio, then I doubt anyone else is going to receive lossless audio, thus making the platform lossy.
Good news for Bluesound! The Bluesound Node 2i successfully streamed lossless audio from Amazon Music HD from 16 bit / 44.1 kHz up through 24 bit / 192 kHz. Amazon's own apps are unable to do what the Bluesound ecosystem can do with respect to playing the highest quality lossless audio.
I used the following music to test, and discovered a couple interesting items along the way.
Neil Young's Greatest Hits, Harvest (2009 Remaster) and After The Gold Rush (2009 Remaster) were all bit perfect at 24/192 from Amazon.
Pearl Jam's Live On Two Legs, Beach Boys' Pet Sounds, and Minnesota Orchestra's Bolero! (Reference Recordings) were bit perfect at 16/44.1 from Amazon.
Jewel's album Spirit never illuminated the HDCD indicator on my Berkeley Audio Design DAC through Amazon, but the same Album lit the light through Qobuz.
The Chicks album Wide Open Spaces was an HDCD master when originally released at 16/44.1. Neither Amazon, Tidal, nor Qobuz streamed a version that illuminated the HDCD indicator on my DAC. There is a 24/96 non-HDCD version available for streaming and I wonder if the 44.1 version is derived from that or if the streaming services have a "bad" copy of the original, or if when the 96 kHz version was done, a 44.1 version was also made and delivered to the services.
I also found what may be the effects of watermarking on a couple albums I tested. The album No Name Face from Lifehouse and the album Pull My Chain from Toby Keith were originally released as HDCD masters on CD. Playing these albums from Amazon Music HD, the HDCD indicator illuminated for about 1 second, then went dark. I've talked to a few people about this behavior and the agreement seems to be that there's a watermark placed on the albums. The watermark didn't effect the first second of the track, but kicks in shortly after, destroying bit perfect playback.
Upon further investigation I found:
- Qobuz plays these albums perfectly and lights the HDCD light on my DAC.
- Tidal plays the Toby Keith album perfect, but not the Lifehouse album.
- Amazon plays neither album perfectly, however Amazon offers a second version of Pull My Chain that does stream perfectly and illuminates the HDCD indicator.
If the watermark is done at the label level this makes a little more sense. The versions that don't playback perfectly are all labeled SKG / Dreamworks. The Amazon version that doesn't have issues is labeled UMG / Dreamworks. Yes, I realize this is a tiny difference in metadata that may mean nothing, but it's the only difference between the albums that playback perfect the those that don't.
Last, I found some MQA content streaming through Amazon Music HD. It's bit perfect as MQA was displayed on my DAC.
The bottom line is twofold. First, it's great that Amazon Music HD can be streamed to a HiFi system losslessly in high resolution. Amazon's own applications are incapable of this, but fortunately the indispensable Bluesound Node 2i handles it with ease. If readers want Amazon Music HD, the Node 2i is a requirement in my book. Second, all of this testing indicates that streaming can be a mess for those of us who like high quality and care about the best sound possible. I think of all the conversations I've had with people who say one streaming service sounds better than another or their local copies of albums sound better than the identical versions when streamed. I completely understand. It's a mess out there.