Description
Rockford Fosgate P400X4 — Four Channels, One Amplifier, Every System Covered
Product Overview
The Rockford Fosgate P400X4 is a Punch Series 4-channel amplifier designed to handle virtually any car audio configuration with a single, compact unit. Rated at 100 watts RMS per channel at 2 ohms 400 watts total it's built for flexibility without compromise. Whether you're running a full 4-way front and rear speaker setup, a 3-way front-stage system, or bridging the rear channels to drive a pair of subwoofers, the P400X4 adapts to your build.
Its real strength lies in versatility. Drop component speakers on the front channels and a pair of subs on the rear bridged and you have a complete front-stage-plus-bass system from a single amp. The onboard Punch EQ with +18dB boost at 45Hz adds low-end weight without a separate processor, while the C.L.E.A.N. gain-setting system makes calibration straightforward regardless of your experience level. For Australian drivers running everything from daily commuters to long-haul tourers, the cast aluminium heatsink keeps the P400X4 stable through the heat.
Key Specifications
- Total RMS Output: 400 watts
- Per-Channel Output: 100W x 4 at 2 ohms
- Channels: 4
- Bridgeable: Yes — rear channels bridgeable for subwoofer use
- Crossover: 12dB/octave Butterworth
- Onboard EQ: Punch EQ — +18dB boost at 45Hz
- Inputs: High-level (speaker-level) and RCA
- Auto Turn-On: Yes — via high-level input detection
- Turn-On Behaviour: Muted (no thump on startup)
- Heatsink: Cast aluminium
- Control Panel Position: Stealth top-mounted
- Protection: Short circuit and over-current
Features & Benefits
- High-Level Input with Auto Turn-On — Connects directly to factory head unit speaker outputs with no RCA cables required. The Auto Turn-On circuit activates the amp when it detects a signal — no remote turn-on wire needed. Ideal for OEM integration in any vehicle.
- C.L.E.A.N. Setup (Clip Level Elimination Audio Notify) — Rockford Fosgate's built-in gain-calibration system removes the guesswork from setup. Get maximum clean output without distortion — no multimeter or test tones required.
- 12dB/Octave Butterworth Crossover — Smooth, predictable roll-off at the crossover point. Configure each channel pair for high-pass or low-pass duties depending on your system — front speakers on high-pass, rear channels on low-pass for subwoofers.
- Onboard Punch EQ (+18dB @ 45Hz) — Adds physical, felt bass impact directly from the amp. No separate bass processor or equaliser needed for most builds — tune it to taste on the control panel.
- Muted Turn-On — Eliminates startup thump that can stress tweeters and expose a sloppy install. Keeps your system sounding professional from the moment the ignition turns.
- Stealth Top-Mounted Control Panel — All gain, crossover, and EQ controls are on the top face of the amp for easy access during setup, then out of sight once installed.
- Cast Aluminium Heatsink — Efficient thermal dissipation for extended listening sessions. Especially relevant in Australian conditions — summer road trips, hot boot spaces, and long outback runs all test an amp's heat management.
- Short Circuit & Over-Current Protection — Built-in protection circuits safeguard the amplifier and connected speakers against wiring faults and load mismatches.
Technical Specs
| Specification |
Detail |
| Total RMS Power |
400W |
| Per-Channel RMS (2Ω) |
100W x 4 |
| Number of Channels |
4 |
| Bridgeable |
Yes (rear channels) |
| Crossover Type |
Butterworth |
| Crossover Slope |
12dB/octave |
| Onboard EQ |
+18dB boost at 45Hz |
| Input Type |
High-level (speaker-level) + RCA |
| Auto Turn-On |
Yes (via high-level input) |
| Turn-On Mode |
Muted |
| Heatsink Material |
Cast aluminium |
| Control Panel Location |
Top-mounted (stealth) |
| Short Circuit Protection |
Yes |
| Over-Current Protection |
Yes |
| RCA Pass-Thru |
Not specified |
| Remote Level Control |
Not specified |
| Dimensions |
Not specified |
| Signal-to-Noise Ratio |
Not specified |
| THD |
Not specified |
| Frequency Response |
Not specified |
| Input Sensitivity |
Not specified |
Compatible With / Goes Well With
System Configurations:
- 4-way full-range speaker system (front + rear, 4-channel stereo)
- 3-way front-stage system (component speakers front, bridged rear channels to subwoofers)
- Front-stage only (component speakers, 2 channels active)
- Rear-fill systems paired with a separate subwoofer amplifier
Head Unit Compatibility:
- Factory/OEM head units (via high-level input with Auto Turn-On)
- Aftermarket head units with RCA pre-outs
Accessories:
- Recommended: use manufacturer-specified power and speaker cables to optimise power delivery (cable spec not provided — confirm with supplier)
Frequently Asked Questions
Can the P400X4 run both speakers and a subwoofer at the same time?
Yes. Run component or full-range speakers on the front two channels and bridge the rear two channels to drive a subwoofer — giving you a complete front-stage-plus-bass system from one amplifier.
Does the P400X4 work with a factory head unit?
Yes. The high-level input accepts speaker-level signals directly from an OEM head unit, and the Auto Turn-On circuit means no remote turn-on wire is needed.
What is the RMS power output per channel?
The P400X4 produces 100 watts RMS per channel at 2 ohms across all four channels, for a total of 400 watts RMS.
What does C.L.E.A.N. setup mean and do I need extra tools to use it?
C.L.E.A.N. (Clip Level Elimination Audio Notify) is Rockford Fosgate's onboard gain-setting system. No multimeter or test tones are required — it guides you to the correct gain level to maximise output without distortion.
Is the P400X4 suitable for a 4-door vehicle with speakers in every door?
Yes. With four independent channels, the P400X4 is purpose-built for full 4-door speaker setups — front and rear — making it an ideal single-amp solution for sedans, SUVs, utes, and wagons.
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