Bluetooth codecs are one of those topics that internet audiophiles fight over just as passionately as whether vinyl is better than digital. The truth is a bit more boring than either side would like to admit.
Here's the deal explained so you can understand it without an engineering degree.
What do codecs actually do?
Bluetooth can't transmit audio as-is – there's too much data and not enough bandwidth. So the audio gets compressed with a codec before transmission and decompressed in the headphones on the other end. The more data a codec can transfer, the less the audio quality suffers from compression.
Basic Bluetooth uses the SBC codec, which is a bit like MP3 in 2003 – it works, but there's better stuff out there. LDAC and aptX HD are both so-called Hi-Res codecs that transfer significantly more data.
LDAC – Sony's data pump
LDAC is a codec developed by Sony that transfers up to 990 kbps at its best. That's roughly three times more than SBC. So in theory, it's a clear winner.
In practice, LDAC operates in three different modes:
- 990 kbps – best quality, but requires a solid connection
- 660 kbps – balanced mode
- 330 kbps – most stable connection, but quality drops close to SBC levels
The problem is that LDAC switches modes automatically based on your environment. On a crowded train or walking around town, the codec might drop to the lowest tier, at which point the whole Hi-Res thing is mostly theoretical. A bit like Henri's Alfa Romeo – stunning on paper, in practice it's sitting at the repair shop.
aptX HD – Qualcomm's alternative
aptX HD transfers 576 kbps. Less than LDAC's maximum, but more than LDAC's economy mode. The key difference is stability: aptX HD stays at the same bitrate and doesn't bounce between modes.
aptX HD requires a Qualcomm chip in both the phone and the headphones. Android phones generally have support, iPhones don't support either of these codecs. Apple uses its own AAC codec, because of course it does.
So which one wins?
Honest answer: depends on the situation.
- You're sitting still in a quiet room – LDAC at 990 kbps transfers the most data and theoretically sounds the best
- You're moving around town or on a train – aptX HD is the more stable choice since it won't drop to a worse mode
- You're using an iPhone – neither works, so this whole discussion is irrelevant to you
According to Jasse, the difference between LDAC and aptX HD is audible, but it requires good source material and a quiet environment. On a Spotify stream, you practically won't notice the difference. If you're listening to FLAC files from your own library, LDAC is the better choice on paper.
The more important question is how the headphones themselves sound. The world's best codec won't save a bad audio signal. Jasse has tuned Valco headphones to sound great regardless of codec – it's just a fact that good frequency response and driver quality matter more than transfer speed.
Valco's VMK25.2 and NL25 support LDAC, so you'll get the best wireless quality out of them with an Android phone. But if you've got an aptX HD phone, that works brilliantly too.
And if you want the absolute best audio quality, plug in a cable. Bluetooth is a compromise – a good compromise, but still a compromise. The VMK25.2 has a 3.5 mm AUX input for exactly this reason.
Every headphone purchase funds our Death Star by roughly 0.000001 percent. Regardless of codec.
