Short answer: AUX can be technically cleaner because it avoids Bluetooth’s lossy audio codec, but on a UE Boom 2 the audible difference is usually modest. Bluetooth is the convenient choice for everyday listening; use AUX when lower latency or a predictable wired connection matters.
What inputs does the UE Boom 2 support?
Logitech lists Bluetooth 4.1, including A2DP, AVRCP and HFP, as well as a 3.5 mm auxiliary input for the UE Boom 2. Its published specifications also include a 90 Hz–20 kHz frequency response, 9 kOhm AUX input impedance, two 45 mm active drivers, two passive radiators and a 90 dBA maximum SPL. Those are hardware specifications, not proof that the two inputs sound identical in every setup. Logitech’s UE Boom 2 specifications
Why can AUX and Bluetooth sound different?
Bluetooth music playback uses the A2DP profile, which requires the SBC codec. SBC is lossy: it discards some source data during transmission. AUX is an analog line connection, so it avoids that Bluetooth codec stage. Bluetooth SIG’s A2DP specification Silicon Labs’ explanation of A2DP audio codecs
That does not mean SBC automatically sounds poor. Bluetooth SIG says SBC can produce “very good audio quality,” close to the limit of what an experienced listener can detect compared with the original stream. Bluetooth SIG on A2DP audio quality
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Will a 3.5 mm cable sound better?
With a modern phone, a strong Bluetooth connection and ordinary streaming content, Bluetooth should sound close to AUX for most listeners. AUX may preserve a little more high-frequency texture or transient detail when the source is revealing, but the outcome also depends on the phone’s digital-to-analog converter, output level, cable condition, speaker volume and EQ.
The UE Boom 2’s small drivers, passive radiators and built-in processing are likely to shape its tonal balance and bass more than a small codec difference. That is an engineering inference from the published hardware, not the result of a controlled UE Boom 2 AUX-versus-Bluetooth listening test. Logitech’s UE Boom 2 specifications
Rank #2
- Portable 360° Sound: The BOOM 4 portable waterproof Bluetooth speaker delivers balanced 360-degree sound with clear audio and bass, so you can enjoy your music in a compact portable design.
- Powered for Adventure: This waterproof portable speaker has a rechargeable battery that stays powered, pumping tunes for 15 hours on a single charge; Charging via USB-C cable (not included).
- A Bluetooth Waterproof Speaker Made for the Outdoors: Rated IP67 waterproof and drop-proof up to 15 feet (1.5 meters), the BOOM 4 floating Bluetooth speaker is virtually indestructible
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To compare fairly, use the same source file, turn off extra phone EQ or loudness processing, and match the volume by ear or with a meter. A slightly louder input often seems better even when its frequency response has not changed. No model-specific controlled test establishes a measured frequency-response difference between these inputs.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.Which connection should you use?
| Factor | Bluetooth | AUX |
|---|---|---|
| Audio path | Uses A2DP and the required lossy SBC codec. | Analog connection; avoids the Bluetooth codec stage. |
| Latency | Wireless buffering can cause delay. | Preferable when lip-sync or playing latency matters. |
| Reliability | Can be affected by interference, pairing or dropouts. | Wired operation avoids radio interference and pairing. |
| Convenience | No cable; practical for phone listening and control. | Requires a cable and a compatible 3.5 mm output. |
| Phone and speaker power | No audio cable, but Bluetooth playback uses the phone’s wireless connection. | Connects the phone’s analog output by cable; the UE Boom 2 still needs its own power. |
Choose Bluetooth for everyday listening
Use Bluetooth when you want to move around, control playback from your phone and avoid managing a cable. With a stable connection, its convenience is usually worth more than the small potential sound-quality advantage of AUX.
Rank #3
- Insanely good 360˚ sound - Ultimate Ears Boom 2 is the 360-degree wireless speaker that blasts loud, insanely great sound with Deep, powerful bass in every direction–everywhere you go
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- Never worry about taking the party too far. Ultimate Ears Boom 2 has 100-ft Bluetooth wireless range; 15-hour rechargeable battery; and the perfect design to bring the music anywhere; Charge time: 2.5 hours
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Choose AUX for lower latency or a more predictable connection
Use AUX for videos, presentations, instruments or gaming when wireless delay is distracting. It is also a practical fallback if pairing is unreliable or radio interference interrupts playback.
Quick Recap
Rank #4
- Ultimate Sound: BOOM 3 delivers loud and immersive 360-degree sound with deep and accurate bass, all carefully balanced so you can hear every note
- Powered for Adventure: Rechargeable battery stays powered and pumping tunes for 15 hours. Add the POWER UP charging dock (sold separately) to charge Ultimate Ears BOOM 3 wirelessly so it’s always ready to go on your next musical adventure
- Super-Portable and Durable: Waterproof + Floats and Virtually Indestructible. BOOM 3 can be totally submerged in up to 1 meter of water for up to 30 minutes, passing seriously tough durability tests to handle life’s spills and thrills
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- PartyUp: Use the Ultimate Ears app to pair 2, 3, 4…and over 150 BOOM and MEGABOOM speakers together for the ultimate sound experience. Works with any generation of BOOM and MEGABOOM speakers
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