Infinity REF3004A Reference 4 Channel Car Amplifier

Four channels. One serious upgrade.

Product Overview

The Infinity REF3004A is a full-featured 4 channel car amplifier built for Aussie drivers who want real, usable power without filling the boot with gear. Delivering 75W RMS per channel at 4 ohms or 200W RMS per channel in 2-channel bridged mode this amplifier is versatile enough to run front and rear speakers today and transition to subwoofer duty when you're ready to add a dedicated sub amp down the track.

Designed to slot into virtually any system, the REF3004A features both preamp and speaker-level inputs, so it works just as well in a factory-stereo setup as it does with an aftermarket headunit. Independent high and low-pass filters on the front and rear channels let you dial in your sound properly no guesswork, no compromise.

Key Specifications

• 75W RMS x 4 channels at 4 ohms
• 100W RMS x 4 channels at 2 ohms
• 200W RMS x 2 channels at 4 ohms (bridged mode)
• 4-ohm stable in bridged configuration
• Variable high-pass and low-pass filters: 32–320Hz, 12dB/octave
• Filters operate independently on front and rear channels
• Preamp and speaker-level inputs included
• Preamp outputs for daisy-chaining additional amplifiers
• Fuse rating: 30A x 2 (two 30A fuses)
• Recommended power and ground lead: 8-gauge
• Wiring and hardware not included

Features & Benefits

• Flexible power modes: Run four speakers at 75W RMS each for a full-system build, or bridge to 2-channel at 200W RMS to power a pair of subwoofers. One amp, multiple system configurations.
• Speaker-level inputs: Connects directly to factory headunit speaker outputs, making this ideal for Aussie utes, SUVs, and 4WDs that still have the OEM head unit in place.
• Independent variable filters: Separate high and low-pass filters on front and rear channels (32–320Hz, 12dB/octave) mean you're not locked into a one-size-fits-all crossover point. Dial in your door speakers and dash separately.
• Preamp outputs: Future-proof your system. Add a dedicated sub amp or processor later without rewiring the whole install.
• Compact form factor: At 320 x 180mm footprint, it tucks neatly under a seat or into a tight boot space a practical win on wagons, dual-cabs, and touring builds.
• Dual 30A fuse protection: Built-in protection helps safeguard your system on corrugated outback roads and long touring runs where electrical stability matters.

Technical Specs

• Channels: 4 (stereo) / 2 (bridged)
• RMS Power (4Ω, 4ch): 75W x 4
• RMS Power (2Ω, 4ch): 100W x 4
• RMS Power (4Ω, bridged): 200W x 2
• Bridged impedance stability: 4 ohms minimum
• High-pass filter range: 32–320Hz, 12dB/octave
• Low-pass filter range: 32–320Hz, 12dB/octave
• Filter assignment: Independent front and rear channels
• Inputs: Preamp (RCA) + Speaker-level
• Outputs: Preamp (RCA)
• Fuse: 30A x 2
• Recommended power/ground wire gauge: 8 AWG (8-gauge)
• Dimensions (W x H x D): 320mm x 55.5mm x 180mm
• Wiring kit: Not included

Compatible With

• Any vehicle with factory or aftermarket headunit (speaker-level inputs allow OEM compatibility)
• Suitable for passenger cars, utes, SUVs, wagons, and 4WDs
• Pairs well with Infinity Reference Series component or coaxial speakers
• Works with 4-ohm or 2-ohm speaker loads (4-channel mode)
• Compatible with 4-ohm subwoofers in bridged mode
• Recommended to pair with a dedicated 8-gauge amplifier wiring kit (sold separately)
• Can be paired with a separate mono subwoofer amplifier using the preamp outputs

Frequently Asked Questions

Does the REF3004A work with a factory (OEM) headunit? Yes. The built-in speaker-level inputs allow you to connect this amplifier directly to the factory headunit's speaker outputs no RCA outputs required on the source unit.

Can I use this amp to power subwoofers? Yes. In bridged 2-channel mode, the REF3004A delivers 200W RMS per channel at 4 ohms, making it capable of driving a pair of 4-ohm subwoofers. Note: bridged mode requires a 4-ohm minimum load.

Do I need a separate wiring kit? Yes. Wiring and hardware are not included. Infinity recommends 8-gauge power and ground leads. A quality 8-gauge amplifier wiring kit is required for correct and safe installation.

What is the physical size of the REF3004A? The amplifier measures 320mm wide x 55.5mm high x 180mm deep compact enough to fit under most seats or in a standard boot install alongside other gear.

Can I add another amplifier using the preamp outputs? Yes. The REF3004A includes preamp (RCA) outputs, allowing you to pass signal to a second amplifier such as a dedicated mono sub amp without the need for an additional signal splitter.