Part II: Comparison of Bluetooth Fidelity - AAC encoder quality (Android 10 & 13, Windows 11, Apple iPhones & Mac)

Greeting everyone, time to jump into Part II of our assessment of lossy Bluetooth music transmission.

In Part I, we examined the use of an Android 10 device (Huawei P30 Pro) as audio transmitter showing the differences between the codecs as played back with the AIYIMA A08 PRO amplifier and its Qualcomm QCC5125 Bluetooth SoC. Please refer to that article for details about the methodology and comparison with the output from a high resolution Topping desktop DAC.

For this Part II, let's focus on the Advanced Audio Coding (AAC) codec which has become a very popular option. Other than the universal default SBC, AAC is probably the most common one for music transmission on account of the fact that the "elephant in the room" - Apple - uses this across its product lines as their standard codec running at 256kbps. Given the amount of use, this is basically a practical standard for quality music transmission over Bluetooth.

Given the broad range of computers/tablets/phones used among family members here, when I'm looking for wireless headphones, I would want to make sure the device supports AAC; probably more so than aptX or LDAC.

Note that there is actually a "family" of AAC profiles from the early Low Complexity AAC (LC-AAC) originating in 1997 up to later versions like Extended High Efficiency AAC (xHE-AAC) released in 2012. As end users, we're generally not privy to such details so I'll just use the generic term "AAC" in this article.

MeLE Quieter2Q (8GB DDR4, 128GB eMMC, Celeron J4125) Mini PC: An inexpensive, silent, multichannel Roon Endpoint. On Paul McGowan (PS Audio): "digital audio is soooo noisy", and "computers are the worst". [+ Windows 11 Update]

MeLE Quieter2Q (~US$250) box and contents. Notice VESA mounting plate (top left) included which is handy I think if used as a monitor back-mounted computer.

Over the last number of years, I've been a Roon user (lifetime membership, no I have not been subsidized in any way by the company). Although not perfect, it works well for me and I've certainly enjoyed the bountiful metadata this interface provides. The Roon software has unified control and access to my music library through Roon Core running on my Windows Server machine. In doing so, this has brought all the hardware playback systems in my home under the same "umbrella" whether it's my Workstation PC (listening to music writing these blog posts), on my phone using Bluetooth headphones while doing housework, or casually streaming Internet radio to the Chromecast Audio - Roon serves them all. The main item on my wish-list is for Roon to support streaming from the library remotely such as from the office.

For those who have read this blog over the years, you'll know that I like multichannel audio playback (discussed here, and here among elsewhere). No, I am definitely not one who thinks 2-channel is somehow "audiophile" territory and that multichannel is the domain of the "home theater guys". Audiophiles IMO should be greedy; we want it all because the love of music and the experience of great sound quality do not end the moment we go beyond 2.0 or 2.1 channel layouts! Some of the best sonic experiences I have had are with multichannel content and hardware.

As you likely know, I've been an advocate for Raspberry Pi devices, like the Pi 3B+ "Touch" and Pi 4 "Touch" builds discussed over the years. I still use these when I run my DAC tests given the convenience of the touchscreen and of course the price represents great value. However, there is a feature which still eludes the Raspberry Pi boards - I want easy multichannel Roon streaming in my main soundroom.