Upgrading a factory car stereo to power an aftermarket amplifier often requires a line output converter (LOC). These devices tap into speaker-level signals and convert them to preamp-level RCA outputs. We researched and compared seven of the most popular models based on manufacturer specifications, published signal-to-noise ratios, and aggregated owner feedback from thousands of reviews. Our evaluation focuses on signal quality, durability, ease of installation, and value.
| Photo | Product | Score | Buy |
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AudioControl LC2i Best Overall 2-channel, AccuBASS, GTO signal sensing, up to 400W per channel input |
9.1 | 🛒 Check Price |
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NVX XCL2 Best Value 2-channel, adjustable input level, 50W per channel max input |
8.7 | 🛒 Check Price |
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PAC LP7-2 Best for OEM Integration 2-channel, 40W per channel input, fixed 200Hz low-pass filter |
8.4 | 🛒 Check Price |
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Kicker 46KISLOC2 Premium Build 2-channel, 40W per channel max input, adjustable output level |
8.2 | 🛒 Check Price |
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Scosche LOC2S Budget Friendly 2-channel, 50W per channel max input, fixed output level |
7.8 | 🛒 Check Price |
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Metra Axxess AX-LOC2 Versatile Install 2-channel, 40W per channel input, adjustable output level, ground loop isolation |
7.5 | 🛒 Check Price |
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Rockford Fosgate RFI2CH Compact Design 2-channel, 30W per channel max input, fixed output level |
7.2 | 🛒 Check Price |
1. AudioControl LC2i: Best Overall
The AudioControl LC2i is widely regarded as the gold standard for two-channel line converters. Its AccuBASS circuit compensates for factory equalization that rolls off bass at higher volumes, restoring a flat response. In our evaluation of spec sheets and owner feedback, the LC2i consistently delivers clean, noise-free signals up to 400W per channel input. The GTO signal sensing eliminates the need for a remote turn-on wire, simplifying installation.
However, the LC2i is not the most affordable option, and its advanced features may be overkill for simple setups. If you have a basic system with a single subwoofer and no bass roll-off issues, a simpler converter may suffice. Also, it lacks a built-in crossover, so you will need an amplifier with one or add an external crossover.
- AccuBASS restores bass lost in factory head units
- GTO (Great Turn On) automatically powers on with audio signal
- Compact chassis fits behind most radios
Pros: Excellent bass restoration; Reliable signal sensing
Cons: Higher price point
2. NVX XCL2: Best Value
The NVX XCL2 offers a solid balance of performance and affordability. It handles up to 50W per channel and provides adjustable output levels to match your amplifier’s input sensitivity. Owner feedback highlights its clean signal reproduction and straightforward installation. The gold-plated RCA connectors resist corrosion, adding to its durability.
On the downside, the XCL2 lacks any bass restoration or signal processing. If your factory head unit has significant bass roll-off, you may need to pair it with a separate processor. It is best suited for budget-conscious builds where the source unit already provides a decent signal.
- Compact and easy to hide
- Adjustable input level from 0.5V to 8V
- Gold-plated RCA connectors
Pros: Great price-to-performance ratio; Reliable build quality
Cons: No bass restoration feature
3. PAC LP7-2: Best for OEM Integration
The PAC LP7-2 is designed specifically for adding a subwoofer to a factory system. Its built-in 200Hz low-pass filter eliminates the need for an external crossover, simplifying the signal path. In our research, it receives praise for its clean signal and easy installation. The auto turn-on feature works reliably with most factory radios.
However, the fixed 200Hz crossover may not suit all subwoofer setups; some users prefer a lower frequency. Additionally, the 40W per channel input limit means it is not suitable for high-power factory systems. It is best for simple subwoofer additions with modest power.
- Built-in 200Hz low-pass filter for subwoofer use
- Speaker-level inputs with auto turn-on
- Small footprint for tight spaces
Pros: Integrated low-pass filter saves space; Reliable auto turn-on
Cons: Fixed crossover frequency limits flexibility
4. Kicker 46KISLOC2: Premium Build
The Kicker 46KISLOC2 stands out for its rugged aluminum enclosure that can withstand harsh environments. It accepts up to 40W per channel and provides adjustable output levels. Owner reviews often mention its solid feel and reliable performance. The included wiring harness and RCA cables add convenience.
That said, its larger size can be a challenge to hide behind some dashboards. Also, the signal quality is adequate but not as pristine as higher-end models like the AudioControl. It is a good choice if durability is your top priority and you have space to mount it.
- Heavy-duty aluminum housing
- Adjustable output level with potentiometer
- Includes wiring harness and RCA cables
Pros: Very durable construction; Complete installation kit included
Cons: Bulky size may not fit all locations
5. Scosche LOC2S: Budget Friendly
The Scosche LOC2S is a no-frills converter that gets the job done for basic setups. It accepts up to 50W per channel and outputs a fixed level. For the price, it offers decent signal clarity, though it may introduce slight noise in some factory systems. Its small size makes it easy to tuck away.
However, the lack of adjustable output level can lead to gain matching issues with some amplifiers, potentially causing noise or distortion. It is best for temporary installations or very tight budgets where some compromise on sound quality is acceptable.
- Very low price point
- Simple plug-and-play design
- Compact size
Pros: Extremely affordable; Easy to install
Cons: No output level adjustment
6. Metra Axxess AX-LOC2: Versatile Install
The Metra Axxess AX-LOC2 includes a ground loop isolation feature that can help eliminate alternator whine in some vehicles. It offers adjustable output levels and comes with mounting hardware. Owner feedback indicates it works well for basic installations, especially in vehicles prone to noise.
However, some users report inconsistent build quality, with occasional units arriving defective. The signal clarity is average, and it may not perform as well as higher-priced options. It is a reasonable choice if you need noise isolation on a budget, but consider a more reliable brand if possible.
- Ground loop isolation to reduce alternator whine
- Adjustable output level
- Includes mounting hardware
Pros: Ground loop isolation helps with noise; Flexible mounting options
Cons: Build quality feels less robust
7. Rockford Fosgate RFI2CH: Compact Design
The Rockford Fosgate RFI2CH is one of the smallest converters on the market, making it easy to install in tight spaces. It handles up to 30W per channel and has a fixed output. Its compact design is its main selling point, and the connectors resist corrosion.
However, its low input power limit means it is not suitable for high-power factory systems. The fixed output level can cause gain matching issues. It is best for very low-power subwoofer additions or as a temporary solution. Most users will be better served by a unit with adjustable output.
- Ultra-compact size
- Simple two-wire connection
- Corrosion-resistant connectors
Pros: Very small footprint; Low cost
Cons: Low input power handling
Frequently Asked Questions
What is a car audio line converter and when do I need one?
A line output converter (LOC) allows you to connect an aftermarket amplifier to a factory stereo that lacks RCA outputs. It taps into speaker wires and converts the high-level signal to a low-level RCA signal. You need one if you want to add an amplifier to your stock system without replacing the head unit.
How do I choose between a 2-channel and 4-channel line converter?
A 2-channel converter is sufficient for powering a single subwoofer or a pair of speakers. A 4-channel converter is needed if you plan to amplify both front and rear speakers separately, or if you want to run a full-range system with front, rear, and sub channels. Choose based on the number of amplifier inputs you require.
What is AccuBASS or bass restoration and do I need it?
Many factory head units reduce bass at higher volumes to protect speakers. AccuBASS (or similar) detects this roll-off and boosts the low frequencies back to a flat response. If you notice your bass disappearing when you turn up the volume, a converter with bass restoration can help. For stock systems without this issue, it may not be necessary.
Can I install a line converter myself?
Yes, installation is generally straightforward if you are comfortable with basic car audio wiring. You need to identify speaker wires, connect the converter’s inputs, and run RCA cables to your amplifier. Most converters include instructions. However, if you are unsure about wiring or vehicle electronics, professional installation is recommended.
Why does my line converter produce engine whine or noise?
Engine whine is often caused by a ground loop or poor grounding. Ensure the converter and amplifier share a common ground point. Using a converter with ground loop isolation can help. Also, keep RCA cables away from power wires and use quality shielded cables. If noise persists, a dedicated ground loop isolator may be needed.
Our Verdict
After researching specifications and owner feedback, the AudioControl LC2i is our top pick for its superior bass restoration and clean signal. For a more budget-friendly option, the NVX XCL2 offers excellent value without sacrificing essential features. Choose based on your system’s needs and budget.
