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We compare products from their published specs and features; the verdicts below are our independent editorial opinions.
If you want a family-friendly set of three wireless over-ear headphones for a car's rear entertainment system, choose Key Audio RP Accessories IR-601B; if you need a single wired in-ear monitor built around a planar magnetic driver and a flat, professional-style frequency response, choose erjigo KZ PR3.
• Key Audio RP Accessories IR-601B — biggest strength: three pairs in one box, infrared wireless freedom, and dual-channel support so two passengers can watch two different monitors without fighting over the screen.
• Key Audio RP Accessories IR-601B — biggest trade-off: infrared is line-of-sight, and it needs an IR transmitter you already own; there's no Bluetooth and no wired fallback for serious listening.
• erjigo KZ PR3 — biggest strength: a 13.2mm planar magnetic driver plus a deliberately professional frequency response curve, meaning it's tuned for accuracy and a wide soundstage rather than a boosted, consumer-friendly smile.
• erjigo KZ PR3 — biggest trade-off: it's wired, single-unit, and in-ear only — no sharing, no wireless mobility, and its flat-ish signature will feel lean to anyone who wants heavy bass out of the box.
• Pick Key Audio RP Accessories IR-601B if you're equipping a car or a family TV setup. Pick erjigo KZ PR3 if you're a musician, engineer, or listener who cares about a neutral, detailed response.
This is a purpose-built product, and it's worth being honest about that. The IR-601B is an infrared wireless over-ear headphone sold as a set of three, designed to pair with the infrared transmitters already built into many in-car rear entertainment systems. It folds flat for storage, runs a dynamic driver rated 20 Hz to 20,000 Hz, and includes a 3.5mm jack alongside its infrared wireless connection. The dual-channel design is the real story: with two monitors in a vehicle, one passenger can listen to the movie on screen one while another tunes to the second channel and watches something else entirely.
Buy it if you're a parent or a driver who wants the back seat quiet and occupied — three pairs in one box is exactly the right count for two kids and a spare. Skip it if you want headphones for music listening, commuting, or anything involving a phone. Infrared needs line-of-sight and a transmitter you supply, so outside a car or a home TV with an IR transmitter, this isn't the tool. Skip it too if you're chasing audio fidelity; this is a convenience product, not a critical-listening one.
erjigo KZ PR3: Who It's For
The KZ PR3 sits at the opposite end of the spectrum. It's a wired in-ear monitor with a 13.2mm self-developed planar magnetic driver, a nano-level silver-plated diaphragm, and 32-ohm impedance — low enough that ordinary playback devices can drive it without a dedicated amp. The manufacturer explicitly markets a professional frequency response curve, which is the phrase that matters most here: the acoustic curve is presented as a strength, and the tuning is described as balanced across bass, midrange, and treble, with clear vocals and instruments rather than a boosted low end.
In practical terms, that makes it a monitoring-oriented earphone. The three points the spec sheet keeps returning to are detail, dynamics, and soundstage — the width and depth of the presentation. If you're mixing, practicing, or just listening critically to classical, rock, or electronic material and you want to hear what's actually in the recording, this is the design intent.
Buy it if you're a musician, audio engineer, or an enthusiast who wants a neutral-leaning, detail-forward in-ear that runs off a phone or laptop. The metal-and-plastic housing is described as lightweight, anti-corrosion, and anti-wear, with memory foam tips that provide real sound isolation, and the silver-plated detachable double-parallel cable is a genuinely unusual touch that helps with signal transmission and durability. A one-year manufacturer warranty is included. Skip it if you want wireless freedom, if you need to share audio with someone else, or if your priority is a thick, bass-forward sound — a flat response is a feature, not a flaw, but it isn't for everyone.
• Best for a car's rear entertainment system → Key Audio RP Accessories IR-601B. Infrared wireless, dual-channel, set of three.
• Best for two passengers watching two different screens → Key Audio RP Accessories IR-601B. That's the entire point of the 2-channel design.
• Best for flat, professional-style frequency response → erjigo KZ PR3. The acoustic curve is the headline feature.
• Best for critical listening and monitoring → erjigo KZ PR3. Planar magnetic driver, balanced tuning, wide soundstage.
• Best for sharing with family → Key Audio RP Accessories IR-601B. Three units versus one.
• Best for use with a phone or laptop → erjigo KZ PR3. 32-ohm impedance means everyday devices can drive it.
• Best for noise isolation → erjigo KZ PR3. Memory foam eartips in an in-ear seal beat an over-ear design.
• Best for long-wear comfort on a road trip → Key Audio RP Accessories IR-601B. Over-ear, around-ear fit built for long sessions.
In my opinion, these two aren't really competitors — they solve different problems, and the right answer depends entirely on which problem is yours. If you're outfitting a car or a family TV setup and want three wireless pairs that just work, I'd buy the Key Audio RP Accessories IR-601B. If you're a musician, engineer, or detail-focused listener who wants a genuinely flat, planar-magnetic in-ear that runs off anything, I'd buy the erjigo KZ PR3. My own pick, if I had to choose one for personal listening, is the KZ PR3 — the planar driver and professional frequency response curve are the more interesting engineering, and 32-ohm impedance means it won't fight your source. Check the current price on Amazon before you commit either way.
does frequency response matter in headphones
Yes, and it's arguably the single most important spec for sound character. A flat response reproduces the recording as-is, which is what the KZ PR3's professional curve is aiming at; a boosted response adds emphasis the artist didn't intend. The IR-601B lists a 20 Hz–20,000 Hz range, which describes coverage, not tuning.
what is the difference between planar magnetic and dynamic drivers
The KZ PR3 uses a 13.2mm planar magnetic driver; the IR-601B uses a dynamic driver. Planar designs typically deliver fast, detailed transients and a wide soundstage, which is why they suit monitoring. Dynamic drivers are simpler, lighter, and well-suited to the wireless, battery-powered format the IR-601B needs.
can I use the KZ PR3 wirelessly
No. The KZ PR3 is a wired in-ear monitor with a 3.5mm jack and a detachable silver-plated cable. There's no Bluetooth or infrared connection listed, so it needs a physical source. If wireless is a requirement, the IR-601B is the one built for that.
do I need a transmitter to use the IR-601B
Yes. The IR-601B is an infrared wireless headphone, and the manufacturer notes an IR transmitter is required but not included. Many in-car rear entertainment systems and some home TVs have one built in — confirm yours does before buying, since infrared also needs a clear line of sight.
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