Hi-Res Audio is one of the few audio terms with an actual definition behind it, which makes its use on wireless products unusually easy to check. The Japan Audio Society administers a certification and a logo, and the requirement for the wired version is straightforward: the equipment must be capable of handling material above CD resolution, in practice 24 bit depth at 96 kHz or higher, through the whole chain. Any manufacturer can use the words without certification, and many do.
Wireless is a separate case with a separate logo, and understanding why it had to be separate explains most of the confusion. A standard Bluetooth audio link does not have the bandwidth to carry an uncompressed 24 bit, 96 kHz stereo stream. That stream needs roughly 4.6 megabits per second. Bluetooth Classic audio in practice delivers a fraction of that. Something has to give, and what gives is the requirement that the audio be unaltered.
What a wireless product is allowed to claim
The wireless certification therefore certifies the codec rather than the transparency of the transmission. It recognizes codecs capable of accepting and reconstructing material above CD resolution, which in current practice means LDAC and LHDC. Both are lossy. They accept a 24 bit, 96 kHz input, discard information according to a psychoacoustic model, transmit at up to roughly 990 kilobits per second in LDAC’s highest mode, and reconstruct something at the original sample rate at the far end. The output is high resolution in format. It is not identical to the input.
aptX Lossless occupies a different position that is often misdescribed. It is genuinely lossless, meaning bit exact reconstruction, but at CD resolution rather than above it. By the certification definition that is not high resolution audio; it is perfect CD audio, which is arguably the more useful outcome and is not what the hi-res logo describes. It also holds that state only while the radio link is clean and steps down to a lossy mode when conditions degrade, which is a behavior no product page communicates. The Bowers and Wilkins Pi8 names aptX Lossless in its published data, which is a specific and checkable claim.
So the honest statement a wireless product can make is narrow: it can carry a high resolution source through a lossy codec designed for that resolution, provided the phone supports the same codec, provided the source material is actually high resolution, and provided nothing in the playback chain resamples it first. Four conditions, all of which have to hold at once.
The source device requirement is the one that fails most often
LDAC is available on a large share of Android handsets because it is part of the Android open source project. LHDC has narrower support. Neither is available on an iPhone, which negotiates SBC or AAC only. A listener with an iPhone cannot obtain a high resolution wireless path from any product on any specification sheet, because the phone will not negotiate a codec capable of carrying one. That is not a criticism of the phone, and it is not a fault in the earbud. It is a fact about what the two devices can agree on.
The Sony WF-1000XM5, the Soundcore Liberty 4 NC and the Nothing Ear all name LDAC in their published specification data, and the Nothing listing names LHDC as well. Those are claims with a named mechanism, and the mechanism can be verified against the buyer’s own handset before purchase. The EarFun Air Pro 4 and the CMF Buds Pro 2 do the same.
The playback chain can quietly undo it
Even with a matched codec at both ends and a genuine high resolution file, the operating system sits in between. Android has historically resampled audio to a fixed rate inside the mixer unless an application takes exclusive control of the audio path, and many streaming applications do not. A file stored at 96 kHz can therefore be resampled down, re-encoded by the codec at its nominal high resolution setting, and arrive at the earbud carrying no more information than a CD rate source would have. Nothing in that chain produces a warning, and no product page describes it. This is the practical reason that listeners chasing the label are usually advised to use a dedicated playback application that can bypass the system mixer, which is a software decision rather than a hardware purchase.
The forty listings that name nothing
Fifty five of the 384 products catalogued here use the words hi-res, high resolution or lossless in their published text. Forty of those name no codec anywhere. In every one of those forty cases the claim is unsupported by the published specification: there is no stated path by which high resolution audio could reach the driver, and no way for a reader to check whether their own phone could supply one.
This is not a small subset of the catalog, and it does not correlate with price. The Technics EAH-AZ100 and its variant the EAH-AZ100 in the alternate finish both carry high resolution language in their listing data with no codec named there, and so does the Rinsmola G21 Pro at the opposite end of the catalog. The pattern is a marketing habit, not a market segment.
Adjacent phrases that carry no definition at all
Hi-Fi, high fidelity, studio quality, audiophile grade and CD quality sound have no administered definition in this context. They can be printed on anything. Where a listing uses one of these instead of a codec name, it has communicated a mood rather than a specification. The same applies to a stated frequency response range extending to 40 kHz on a wireless product, since no Bluetooth codec in common use transmits content there and the human hearing range does not extend there either.
What the label is worth in practice
Even where every condition is satisfied, the audible difference between a well implemented AAC connection and LDAC at its highest mode on typical streaming material is small and contested. Most streaming catalogs deliver already compressed audio, so a high bitrate Bluetooth codec is re-encoding a file that has already lost information. The genuine beneficiaries are listeners playing locally stored high resolution files on an Android handset with a matched pair of earbuds, which is a real use case and a narrow one.
Set against that, the variables that reliably change what a listener hears are the seal, the ear tip size, the tuning applied by the manufacturer and whether noise cancelling is engaged. A poor seal costs more low frequency energy than any codec choice can recover. The Sennheiser Momentum True Wireless 4 and comparable models across the wireless earbuds section and the earbud headphones section vary far more in tuning than in codec support.
The workable rule when reading a listing is to ignore the resolution claim and look for the codec name. If a codec above SBC and AAC is named and the buyer’s phone supports it, the claim has substance. If no codec is named, the correct conclusion is that the specification does not support the claim, and the question to ask a seller is simply which codecs the product negotiates. Nothing about resolution justifies raising listening volume: sustained loud listening damages hearing permanently regardless of the bit depth involved.
