The curve that stays on the dongle
A free Apache EQ app that writes a headphone curve onto an unofficial list of USB dongles, and then leaves the phone.
- Category
- Consumer
- Who it is for
- Someone who already owns one of the listed dongles and more than one pair of headphones.
- Possible model
- Open source
- Difficulty
- Hard
- Inspired by
- Contour · Contour
- Original launch
- Watch the launch · Oct 17, 2026
Difficulty is an editorial estimate of technical and operational complexity, not a score.
Startup idea analysis by Startup Ideas. Last reviewed Oct 17, 2026. How we read a launch.
The startup idea
Chronosaur posted Contour on October 17. A free, open-source EQ app for USB DAC dongles on Android. Protocol Micro and Max, FiiO KA15, K13 R2R, SnowSky Melody and Tiny A, more coming soon. The site is contoureq.app and the repository is Chronosauros/contour. The page says one thumb edits a parametric curve, a hold sends the profile to the dongle, and the dongle stores it, so it works with every app and every device you plug the dongle into. It shows only the controls that dongle has. It needs Android 9 or newer with USB OTG. The app has no internet permission, no accounts, and no analytics, so nothing leaves the phone. The same page says this website counts anonymous visits, without cookies. The license is Apache 2.0. Made by Chronosaur. Unofficial, not affiliated with or endorsed by CrinEar. It writes to hardware, so use it at your own risk. The post does not say unofficial, and it does not name Android 9. This page did not install the APK.
The opportunity is the profile that stays on the dongle after the phone is gone. A smaller product is one supported dongle and one curve, with the risk on the screen. The post says free and open source. The page agrees, and adds that the hardware write is unofficial.
Do not say CrinEar ships this. The footer says they do not. Do not say the website is as quiet as the app. The page counts visits.
The problem
A parametric EQ is a table on a computer, and the dongle forgets it when you change headphones.
Who would pay for this?
- Primary
- Someone who already owns one of the listed dongles and more than one pair of headphones.
- Secondary
- A person who will read the hardware warning before the first hold.
- Early adopter
- One dongle, one profile, the unofficial line.
How could it make money?
Possible models. Nothing here is a claim about what Contour charges.
- No price. Apache 2.0.
- The app has no account.
- A second app, EQ Sweep, is linked as a helper. This page did not price it.
What would the MVP look like?
- A curve edited with a thumb.
- A hold that writes it to the dongle.
- The device list, including the ones that are not here yet.
- The unofficial and hardware lines.
How to validate the idea
- Ask five owners to unplug the phone and listen on another device.
- If the curve is gone, the dongle was not storing it.
- Do not add a dongle the page has not named.
How to differentiate
- The EQ lives on the dongle, not in one music app.
- The control set changes with the hardware.
- Apache, and unofficial.
- Do not become a store for headphone measurements.
Why this could be interesting now
The post and the page agree on the dongles and on free and open source. Only the page says the write is unofficial, that Android 9 is the floor, and that the site counts visits the app does not make. The opening is one curve that survives the unplug, with that warning beside it.
Original product launch
This launch is inspiration and evidence that someone shipped, not a partnership. The idea above is our reading of the broader opportunity. Contour did not write it.
- Product
- Contour
- Source
- Contour
- Film
- Contour, unofficial and on the dongle
- Posted
- Oct 17, 2026 · 0:51
Product that inspired this idea
Chronosaur's post says Contour is a free, open-source EQ app for USB DAC dongles on Android. Protocol Micro and Max, FiiO KA15, K13 R2R, SnowSky Melody and Tiny A, with more coming. The site lists the same dongles and says more are coming. It needs Android 9 or newer with USB OTG. The app has no internet permission, no accounts, and no analytics. The website, separately, counts anonymous visits without cookies. The license is Apache 2.0. The footer says it is unofficial, not affiliated with or endorsed by CrinEar, and that it writes to hardware, so use it at your own risk. The post does not say unofficial. This page did not plug in a dongle.
Posted by @soundblooms. Watch the original launch. No separate product site is listed unless the post itself is the source.
- android
- audio
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