The Shanling UP4 has been around long enough now that it has gone through a hardware revision, and it remains one of the more practical ways to add balanced Bluetooth output and USB DAC functionality to headphones that otherwise only have a passive cable. I have used the current 2022 revision as a bedside and travel amp for a while, so here is how it actually holds up.
What the UP4 Actually Is
The UP4 is a small clip-on style Bluetooth amplifier and DAC, meant to attach to your headphone cable or sit in a pocket while paired to a phone or DAP over Bluetooth. The 2022 revision uses two ES9219C DAC chips, an upgrade from the ES9218P chips in the earlier version, and supports the full range of current Bluetooth codecs including LDAC, LHDC, aptX HD, aptX Low Latency, aptX, AAC, and SBC.
Two Ways to Use It
- As a Bluetooth receiver: pair the UP4 with your phone or DAP over Bluetooth 5.0, then connect your wired headphones to the UP4’s 3.5mm or 2.5mm balanced output.
- As a wired USB DAC: connect the UP4 to a computer or phone via USB-C, bypassing Bluetooth entirely for a fully wired, potentially higher-fidelity connection.
Both modes work well in practice, and switching between them is just a matter of whether a USB-C cable is plugged in or not. I found myself using Bluetooth mode most days for convenience and switching to wired USB mode specifically when I wanted the best possible sound quality from a laptop for focused listening.
Battery, Certification, and Practical Details
- Rated up to 15 hours of playback via the 3.5mm single-ended output
- Certified Hi-Res Audio and Hi-Res Wireless Audio by the Japan Audio Society
- Aluminum alloy CNC body with 2.5D glass panels on both sides
- One-touch NFC pairing for quicker Bluetooth setup with supported phones
The NFC pairing is a small feature that ends up mattering more than expected in daily use, since tapping a phone to the UP4 is genuinely faster than digging through a Bluetooth settings menu every time you want to reconnect after the device has been idle.
Sound and Real-World Performance
Over Bluetooth with LDAC enabled on a compatible phone, the UP4 sounds clean and reasonably detailed, clearly a step above a phone’s built-in headphone output where one still exists, and obviously better than Bluetooth audio straight from a phone with no dedicated DAC at all. The dual ES9219C setup keeps background noise low even with sensitive IEMs, which is not always guaranteed on cheaper Bluetooth amp modules.
Switched to wired USB mode, there is a noticeable step up in clarity and a slightly blacker background, which makes sense given Bluetooth codecs, even good ones like LDAC, still involve some compression overhead compared to a direct USB connection. If outright sound quality matters more to you than wireless convenience on a given day, the wired mode is worth defaulting to. Current availability and pricing can be checked through Linsoul’s listing for the 2022 revision.
Fit and Comfort for All-Day Wear
Since the UP4 is meant to clip onto a cable or sit in a pocket rather than be handled constantly, comfort comes down to weight and cable management more than anything else. At its size and weight, I did not notice it dragging on a shirt collar during a full day of wear clipped near the collarbone, which is a common complaint with bulkier Bluetooth amp modules. The 2.5D glass panels do pick up fingerprints and small scratches over time if you are not using a case, so if you plan to keep it clipped and exposed daily rather than in a bag, a basic protective sleeve is worth the small extra cost.
Button placement is sensible too, with a distinct feel between the volume and playback controls so you can operate it by touch alone without accidentally skipping a track while trying to adjust volume, a small thing that a surprising number of competing devices get wrong.
Frequently Asked Questions
Does the UP4 support multipoint Bluetooth connections?
The UP4 pairs with one active source device at a time rather than supporting simultaneous multipoint connections, so switching between two paired devices requires reselecting within Bluetooth settings.
What is the difference between the original UP4 and the UP4 2022?
The 2022 revision upgraded the DAC chips from ES9218P to ES9219C, generally improving measured performance while keeping the same overall form factor and feature set.
Can the UP4 be used with a laptop as a standard USB DAC?
Yes, connecting via USB-C lets it function as a USB DAC for a computer, bypassing Bluetooth entirely for the wired listening mode.
Does the UP4 support aptX Adaptive?
The UP4 supports aptX, aptX HD, and aptX Low Latency, but aptX Adaptive specifically is not part of its codec list, which is worth checking if that particular codec matters for your source device.
Pairing With Older Headphones
One underrated use case for something like the UP4 is breathing new life into a pair of wired headphones you already own and like, but that otherwise have no wireless functionality at all. Clipping the UP4 onto the cable of an older pair of headphones I have had for years turned them into a fully wireless setup instantly, without needing to replace headphones that still sound great and fit well. For anyone sitting on a favorite pair of wired cans wondering whether to replace them just for Bluetooth convenience, this is a cheaper and arguably better-sounding alternative to buying new wireless headphones outright.
Conclusion
The Shanling UP4 remains a solid, flexible option for adding real DAC and amplification quality to wired headphones without committing to a full-size portable amp. The dual-mode Bluetooth and USB functionality covers most practical use cases, and the 2022 chip upgrade keeps it competitive against newer alternatives at a similar price.
Used as a daily Bluetooth and wired amp over several weeks with a rotation of IEMs. I have a computer science degree and write about portable audio hardware regularly.