In this article, I review the Simphonio Charm (PH-3) on-ear headphones. The Charm features open-back retro styling and a 70mm planar magnetic driver. It’s priced at $299.

Disclaimer: This sample was provided by Simphonio Audio for an honest review. All observations and opinions here are my own, based on my experience with the product.

Simphonio Charm (PH-3)

What’s in the Box

• Simphonio PH-3 headphones
• Detachable modular cable
• Carrying case
• 1x pair of foam earpads
• 1x pair of faux leather earpads
• 3.5mm and 4.4mm plugs

Design

The PH-3 keeps things relatively simple in terms of design, but there’s still enough going on to make it stand out. The all-metal circular ear cups have a clean, functional look, with a vented outer grille that subtly hints at the planar driver inside.

The headband is one of the more distinctive elements. It uses a spring steel frame paired with a suspended leather strap, which helps keep the weight down while maintaining a secure fit. The adjustment mechanism is straightforward, with a perforated metal slider that feels sturdy and easy to work with.

Build quality is solid overall. The CNC-machined aluminium ear cups give it a reassuring sense of durability, while the matte finish keeps things looking tidy in daily use. It doesn’t feel overly premium, but there’s nothing cheap about it either.

At around 310 grams, it’s also noticeably lighter than most full-size planar designs. That alone makes it feel a bit more practical for regular use, rather than something you only reach for at your desk.

The Charm is a comfortable headphone overall. The wide leather strap distributes pressure evenly across the top of your head, which helps over longer sessions. The clamping force felt a bit tight at first, but I got used to the on-ear fit after a couple of days.

Interestingly, my ears actually fit inside the earpads, so it ends up feeling more like a mini full-sized headphone, if that makes sense. Speaking of earpads, the PH-3 comes with both foam and vinyl options. They’re both comfortable, but I prefer the foams as they breathe a bit better.

Sound

Sources used for testing include the Luxsin X9, iBasso DX260 MK2 and Muse HiFi M6 Double. The Charm is pretty easy to drive, so you don’t need to worry too much about power. That said, it still scales nicely with higher-end sources.

What stands out most about the PH-3 is the way it balances richness with clarity. Planar headphones often lean one way or the other, but here you get a sense of body and warmth without losing definition. Notes have a natural weight to them, yet the presentation remains clean and well-resolved.

There’s also a very convincing sense of timbre. Instruments and vocals come through with a realistic tone, avoiding the slightly artificial or dry character that some planar designs can fall into. It ends up sounding more organic than expected, while still maintaining strong overall clarity.

Bass

The bass is deliciously fast and disciplined, but it doesn’t sacrifice body or note weight to achieve this. The properties of modern planar drivers really pay dividends here.

Sub-bass extension is surprisingly good. It’s not going to rattle your skull, but there’s enough depth and a light, controlled rumble to give it some presence down low. The mid-bass is slightly more elevated, adding a welcome bit of punch and keeping things engaging but without smearing the mids.

Midrange

Some headphones simply do midrange better than others, and the Simphonio Charm falls into that category. It strikes an excellent balance between warmth and clarity, with enough body to sound natural, but enough presence to stay engaging.

Male vocals come through with good weight and authority without sounding overly thick. Female vocals, on the other hand, have a smooth, slightly euphonic quality that makes them easy to listen to, while still carrying a sense of air and delicacy.

The timbre sounds very natural throughout. Voices and instruments sound convincing and unforced, to the point where you stop focusing on the headphones and just get lost in the music.

Treble

The treble is a bit of a tricky one. For the most part, it doesn’t draw attention to itself, as you’re more focused on the overall presentation. That said, it’s doing a lot of heavy lifting behind the scenes.

There’s enough energy to keep things crisp and well-defined, but without any sharpness or artificial edge. It comes across as smooth and controlled, with enough air to open things up and give the presentation a bit more space.

At the same time, it’s surprisingly resolving. The Charm brings out a good level of micro-detail without ever feeling forced or fatiguing, which is not an easy balance to get right.

Soundstage & Technicalities

I find a lot of open-back headphones don’t quite deliver on their promise of soundstage. It often feels more like a spec sheet talking point than something you actually hear.

The Simphonio Charm, on the other hand, creates a genuinely spacious presentation without thinning things out. There’s still a good sense of note density and realism, which helps it sound more convincing overall.

Separation is strong, with the planar driver keeping things clean and organised, and imaging is impressively precise. It’s easy to place elements in a mix, whether you’re listening to music or playing games.

Verdict

The Simphonio Charm (PH-3) is one of the more exciting headphones I’ve come across in a while. It’s the kind of set that keeps pulling you back in, not because of any one standout trait, but because the overall tuning just works so well.

The on-ear fit does take a bit of getting used to, and while I found them comfortable, they don’t quite match the ease of most modern full-sized headphones for me. Others may well find them perfectly fine, but it’s something worth keeping in mind depending on your preferences. That said, once you settle in, the trade-off feels worthwhile.

The audio quality here is genuinely outstanding, with a natural, engaging presentation that’s hard to come by at this level. Build quality is excellent too, with a design that feels both thoughtful and well executed.

If you’ve been on the fence about the Charm, or on-ear headphones in general, this is an easy one to recommend.

Specifications

• Model: Simphonio PH-3
• Type: Over-ear Planar magnetic driver headphones
• Driver: 70mm Planar magnetic driver
• Frequency response range: 5Hz ~ 50kHz
• Dynamic impedance 16Ω ±15%
• Output sound pressure level: 105 ± 3dB/mW
• Maximum power: 500mW
• Cable length: 1.2m
• Interface: 3.5 plug / double 3.5 pins
• Weight: 310g