
Topping has added crossfeed processing to its DX5 II DAC to process audio and make headphone listening sound closer to stereo speakers.
The update is free, while the DX5 II costs around £300.
Topping has given its high-spec DX5 II DAC and app an interesting free upgrade – and it's designed to make your headphones sound less like headphones.
The firmware upgrade adds a new, user-selectable feature in the form of headphone crossfeed processing, which aims to make your experience sound more like you're listening to speakers.
Crossfeed processing attempts to address one of the most important differences between listening on headphones and stereo speakers.
With the former, you get the left channel in your left ear and the right channel in the right. But with speakers you get a mix of the channels, so your left ear will hear a bit of the right speaker and vice-versa.
You'll also get reflections from the surfaces in the room. And Topping's system aims to replicate that.

Topping DX5II headphone crossfeed: how does it work?
Topping's technology is designed to simulate head-related transfer function, or HRTF for short. That's the same phenomenon simulated in headphone binaural audio and virtual surround sound, and it influences how our ears hear sound emanating from a particular point in space.
By using an algorithm to adjust frequencies to mimic HRTF, you can make sounds appear to be coming from specific places.
Topping says that its system "balances tonal accuracy with realistic spatial presence, avoiding the distortion that can result from simply flattening frequency response".
There's also a second, simpler crossfeed mode that adds a bit of speaker while "maintaining more of the typical characteristics of headphone listening".
This isn't the only system that attempts to replicate speakers: BeyerDynamic has recently launched a plug-in for music producers that makes its studio headphones more speaker-like to help with mixing, because music mixed solely on headphones is often very different to listening through speakers.
I've found that helpful for fixing mixes myself, but it does introduce some of the distortion that Topping describes, so a distortion-free setup could be quite something.
The firmware update is available now for all existing customers, and the DX5 II is available to buy with a recommended retail price of £299 (about €344 / $411 / AU$587).