Fosi Audio PH04 4 Channel Headphone Amplifier Stereo Audio Amp
Quick take
The Fosi Audio PH04 is a compact, wired 4-channel headphone amplifier that lets you run the same audio to up to four listeners with independent volume controls. It’s a practical pick for home studios, e-drums setups, and TV or group monitoring when everyone needs their own level. The main caveat is connection support: it works with 3.5 mm headphones, and 6.35 mm users will need a 3.5 mm to 6.35 mm adapter.
Pros and cons
Pros
- 4-channel design with dedicated level control for each output, useful for shared monitoring.
- Metal enclosure and an on/off switch, designed for desk or stage practicality.
- Comes with a 12V DC power adapter, simplifying setup for studio use.
- Compact footprint makes it easy to place around other gear.
Cons
- Headphone connection flexibility depends on what plug you have, 6.35 mm typically requires an adapter.
- One limitation reported is distortion when turning knobs high on certain laptop headphone sources, so source choice matters.
- Independent volumes control level, but this is not a wireless or multi-input mixer style solution.
What buyers think
Buyer-review evidence is broadly positive on the PH04’s core job, splitting one audio signal to multiple headphone outputs and making it easy for different listeners to dial in comfortable volume. Users commonly mention that independent volume controls are especially important when headphones have different sensitivity or impedance. The build is frequently described as solid, and the unit’s compact size works well for desk setups.
What it is and who it’s for
The PH04 is a 4-channel headphone amplifier meant for situations where one audio feed needs to reach several people at once. Instead of sharing the same headphone level, each output has its own volume control, so listeners can adjust their comfort independently.
This makes it a good fit if you regularly run:
- Studio tracking and overdubs, where multiple musicians need a click or mix in their own preferred loudness.
- Shared listening for TV or playback during rehearsals, interviews, or watch parties.
- Practice setups like e-drums, where you want a straightforward way to drive multiple headphone mixes from a single source.
Connectivity and setup essentials
The amplifier is designed around a wired headphone output approach and includes a 12V DC power adapter. For headphone compatibility, it supports standard headphone connections, including 3.5 mm. If you plan to use 6.35 mm (1/4 inch) headphones, you will typically need a 3.5 mm to 6.35 mm adapter.
In real-world use, the biggest “gotcha” tends to be source matching. If your source device is already struggling to drive a headphone load through a splitter, you may hear artifacts as volume approaches the upper range. If possible, test with the exact playback or interface output you plan to use day to day.
Pros and performance in everyday use
Independent volumes help when headphones differ
A major reason buyers like multi-output headphone amps is that headphones do not all respond the same way.
Sound quality and behavior at higher volume levels
Across review themes, the PH04 is treated as a functional utility for monitoring and headphone distribution. The takeaway: pairing with a clean, appropriate headphone/line output matters, and you should expect the upper volume region to be more demanding.
Value and build quality
At its category price point, the PH04’s appeal is the feature set for the money: four outputs, individual volume control per channel, and a metal housing. Buyers also tend to like the practical, no-fuss footprint for studio desks and stage environments where space is limited.
Limitations to consider before you buy
- Adapter needs for 6.35 mm headphones: if your headphones are 1/4 inch, confirm you have the right adapter (a 3.5 mm to 6.35 mm adapter is mentioned as a requirement).
- Source-dependent behavior at loud settings: if you plan to push it near maximum volume from a laptop headphone jack, consider testing your specific source first.
- Not a multi-input, feature-rich mixer: it is focused on headphone distribution and level control, not on switching between multiple audio inputs.
How it compares for different buyer types
Choose the PH04 if you need a simple 4-way headphone utility
If your priority is one audio feed to multiple listeners with independent levels, the PH04’s 4-channel design aligns well with that workflow.
Consider alternatives if you need more flexible inputs or wireless
If your project requires mixing multiple sources, Bluetooth, or other advanced routing features, a more capable headphone mixer or distribution solution may fit better. Also consider options that explicitly support your headphone connector type without adapters.
Verdict
The Fosi Audio PH04 is a solid, budget-friendly headphone amplifier/splitter for shared listening and studio monitoring, especially when you want four separate volume controls. It’s most compelling when you have a straightforward single audio output to distribute, and you do not mind using a 3.5 mm to 6.35 mm adapter if needed. If you plan to run from a laptop headphone jack and crank levels near maximum, treat source pairing as a key part of getting clean results.
FAQs
Is the Fosi Audio PH04 good for studio monitoring?
Yes. It is designed to send one audio feed to up to four headphone outputs with independent volume control per channel, which is useful during tracking and monitoring sessions.
Will the PH04 work with 6.35 mm (1/4 inch) headphones?
It supports standard headphone output types, and for 6.35 mm headphones you will typically need a 3.5 mm to 6.35 mm adapter.
Does it include a power adapter?
Yes. It comes with a 12V DC power adapter.
Can different listeners control their own volume?
Yes. The PH04 provides dedicated output level control for each channel.
Why might I hear distortion at high volume from my laptop?
Some sources may not drive cleanly through a splitter-style amplifier setup at very high volume settings. If that happens, try testing with a different audio source or interface output and confirm headphone levels with the specific devices you plan to use.
Specifications
| Product Title | Fosi Audio PH04 4 Channel Headphone Amplifier Stereo Audio Amp with 12V 1A Power Adapter Ultra-Compact Portable Headphone Splitter for Studio and Stage |
|---|---|
| Category | Electronics > Headphones, Earbuds & Accessories > Amplifiers |
| Brand | Fosi Audio |
| Manufacturer | Fosi Audio |
| Model Name | Fosi Audio PH04 |
| Model Number | PH04 |
| Form Factor | In Ear |
| Connectivity Technology | Wired |
| Noise Control | None |
| Item Weight | 0.38 Pounds |
| Color | Red |
| Brand Name | Fosi Audio |
| Built-In Media | 12V DC power adapter*1, Use manual*1 |
| Age Range Description | Adult |
| Warranty Description | 18-month manufacturer |
| Customer Package Type | Standard Packaging |
| Number of Items | 1 |
| Is Autographed | No |
| Headphones Ear Placement | Over Ear |
| Headphone Folding Features | In Ear |
| Control Type | Button Control |
| Control Method | Touch |
| Impedance | 4 Ohms |
| Enclosure Material | Metal |
| Specific Uses For Product | Studio, Sport, Video Game, Music |
| Antenna Location | Calling, Gaming |
| Compatible Devices | headphones |
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