There appears to be a lot of confusion about the various Bluetooth transmitter/receiver products and what they can and cannot do, and what is required to get the benefits of advances in Bluetooth technology. To clarify, there are currently three ‘flavors’ of music quality...
There appears to be a lot of confusion about the various Bluetooth transmitter/receiver products and what they can and cannot do, and what is required to get the benefits of advances in Bluetooth technology. To clarify, there are currently three ‘flavors’ of music quality audio Bluetooth- A2DP, AptX and AptX LL. A2DP is standard Bluetooth that most cell phones, computers, wireless headphones and speakers use. It is serviceable with decent audio quality but up to ½ second of delay. When just listening to music, the delay doesn’t matter, but for watching TV it can be annoying, leading to a batter hitting a ball and the sound coming a beat later, or messing the sync of lips with the words they’re saying. AptX has been around for a while as a higher quality version of Bluetooth audio, with better sound quality and less delay, but relatively few devices support it and it still has a delay of roughly 1-2 tenths of a second. Better than A2DP, and good enough for people who aren’t as sensitive to the delay. But obvious and annoying when the TV sound is on (for people in the room), while someone is listening through wireless headphones.
So the AptX people developed AptX LL, standing for ‘Low Latency’, a fancy term for low delay. AptX LL delay can be as low as 40 milliseconds (less than half of a tenth of a second), and for TV watching, is almost undetectable. In order to benefit from AptX LL however, you need a source that is transmitting it and a headphone or speaker that is receiving and reproducing it. This is where I think a lot of negative reviews are coming from- if you don’t have AptX LL at both ends, you won’t get any benefit. Since there are only a handful of AptX LL headphones, and no TV or hifi manufacturers have adopted it yet, miniature devices like the DUO S are designed to let the vast majority of existing audio devices take advantage of this technology.
The Trond Duo S provides the most advanced Bluetooth audio experience currently available, and I am very happy with its performance. I bought it specifically to obtain satisfactory wireless headphone listening to my Sony XBR TV. When connected to a continuous source of power via the microsd port, it pairs almost instantly when I turn my headphones on (note many TV’s kill the power to their USB ports when they are turned off, and the Trond will shut off after some time to save the battery, and then need to be turned back on and re-paired when the TV is turned back on, so I would recommend using an old phone charger to power it). I’m using the Avantree Audition Pro, one of the only headphones on the market with AptX LL built in, and the sound is excellent, with negligible delay. The DUO S can also act as a receiver, to turn any pair of headphones with an ⅛” jack into AptX LL wireless headphones, but of course you need two of the DUO’s, one transmitting from the TV or other device and one connected to the headphones.
Finally, I must comment on Trond customer service. This has been by far the most responsive company I’ve done business with in the internet age. We’re talking a $40 device from China. I was not expecting much when I emailed them a question. And yet I have experienced a level of communication that would make Apple envious. My emails were responded to promptly, in detail, by individuals with excellent spelling and grammar who clearly want my experience to be as positive as possible. I originally had some issues with getting the LL version of AptX working with my Avantree Audition Pro’s, and instead of blaming the other company, Trond bent over backwards to get to the bottom of the issue and offer solutions. So 5 stars for Trond customer service as well as the DUO S.