Hey, WondrousHippo (and others) -- I just struck out on the Avantree BTDG-60, which turns out to be compatible with Bluetooth 2.0 but not to play well BT 3.1. My high-end Windows 10 Pro laptop has only BT 3.1 and "ThunderBolt 3" (USB-C, I think) ports. So does anyone know of other BT dongles that support aptX HD, identify the Codec being used, and are compatible with the newer BT specs? -- JClarkW
I do not follow what you mean by "... compatible with Bluetooth 2.0 but not to play well BT 3.1. My high-end Windows 10 Pro laptop has only BT 3.1 ..." Do you mean USB instead of Bluetooth and BT? In any case, I believe that Avantree model does not support AptX HD, and I am skeptical it would accept a USB PCM input. Its USB 2.0 port if any is likely for charging only.
Your Windows 10 Pro laptop is unlikely to provide AptX HD BT transmission unless it specifically lists that capability. I was surprised that Win 10 does support AptX, according to the Helge Klein blog that Vincent Kars linked to (though not the LL or HD versions). My understanding is that to get AptX HD BT transmission, the computer or device needs a Qualcomm CSR8675 chip onboard. The newer Qualcomm QCC5100 series chips also support AptX HD while consuming less power, but only as receivers per my understanding. So you will have to use an external BT transmitter with your laptop. I guess most people stream from their phones via BT with SBC codec to a BT receiver in their music system, such as in the D50s, and don't worry about or know about getting AptX HD quality.
The availability of Bluetooth transmitters providing AptX HD or better codecs unfortunately remains limited, even though several high quality AptX HD and LDAC BT receivers are available. I have bought three generations of AptX HD BT transmitter, starting with the first gen where the build quality and reliability was somewhat poor. The latest gen is pretty decent, and I bought two such transmitters last year. If you search for "AptX HD" on Amazon, you will get some 13 pages of hits, many if not most of them false positives. Before AptX HD came along (and even after, to deliberately confuse buyers I feel), BT transmitters were titled and/or advertised as "AptX LL for HD audio", so several of the hits you get give you only LL and not HD. There are perhaps three basic models that are re-branded by different sellers, but seem identical, sometimes down to the pics of happy families. For example, the following two:
Giveet, no battery ;
Giveet, with battery .
Last year, I got both the "no battery" one listed above, and I got another with a battery similar to the "battery" one listed above but with a different branding. The one without the battery is less than two-thirds the size of the other one. They both work well for me. Most of the units are priced around the same ($35 to $40), but the ones I listed seem to have a slightly better Amazon user rating than the others, perhaps because the seller provides better service and support. Do not get the models without an antenna or two; the antenna enables a larger transmission range. These units which can be used as either transmitter or receiver, provide both 3.5mm AUX analog as well as digital optical S/PDIF TosLink for both input and output. You can search Amazon for "usb to optical audio adapter", and you will come up with some possible small and economical solutions on connecting your laptop to the above BT transmitters. Or you might use an external sound card attached to laptop via USB, with TosLink output. However, I have not investigated this. I use an HDMI audio extractor between my Blu-ray player and my TV, to get a TosLink optical output to the input of the "no battery" BT transmitter, and power the latter by USB from a phone wall charger. Last year, I was using a Topping D10 driven via USB from my desktop computer, and using the D10's TosLink optical output (there is also a Sabaj or perhaps SMSL model with a similar output) to the "with battery" BT transmitter's input, and continuously powering the latter with USB from a phone wall charger as well. After a recent change of address, I cannot find the D10 hidden in one of many boxes, so I now use the analog headphone output of my desktop amp (fed by a DAC fed via USB by my computer) to get an input to the 3.5mm analog input port of the BT transmitter. I pair each BT transmitter with a separate Radsone ES100 (bought them before there was even a single user review on Amazon) that I use to drive earphones. Both digital and analog connections work well for me, and give me high-enough quality sound while freeing me to move around. I get visual confirmation through the lit indicators of both the transmitter and the ES100 that the BT connection is via the AptX HD codec.
If you cannot find a small usb-to-optical converter to function as the D10 did in my setup, then you might consider a high-quality USB dongle DAC like the HiDizs S8 / Tempotec Sonata or a Meizu which both reviewed well here on ASR, and cost about $30. Use it as a USB DAC on your laptop, and use its 3.5mm headphone out as input to the BT transmitter. An overkill option (and more expensive) would be to use a HiDizs AP80 Pro or HiBy R3 Pro as a USB DAC on your laptop, and these DAPs already have AptX HD and even LDAC capability to transmit to your D50s, so you could skip the Giveet BT transmitters I listed above. IIRC the HiBy has two-way BT, you would have to check about the AP80 Pro.
As member "Jimmy" posted above, Bluetooth 5.2 will bring big improvements to audio standards, and hopefully simplify the convoluted signal routing I described in the preceding.