Quick answer
Choose the Kicker CX400.1 if you have a single moderate-power sub and want to save money and space. Step up to the Kicker 43CX1800.1 if your subwoofer is rated for high power and you plan to run it at one ohm for maximum output.
Power and one-ohm stability: the real dividing line
The 43CX1800.1 is built for big bass, while the CX400.1 is a more modest mono amp. Both are one-ohm stable, so either can extract extra output from a compatible sub, but the 1800.1's higher power ceiling means it can drive a high-power sub closer to its limits. The CX400.1 suits a single sub that doesn't need huge wattage. Match the amp's power to your sub's RMS rating rather than buying the biggest amp available.
Remote bass control and installation footprint
Both amps offer an optional remote level control to adjust bass from the dash, a handy feature if you want to tame bass on the fly. The difference is physical: the 43CX1800.1 is larger and heavier, so check under-seat or cargo-area space before committing. The CX400.1's smaller chassis fits tighter locations. Neither amp includes the remote as standard per the catalog, so budget for it separately if you want dash control.
Price and value trade-off
The CX400.1 lists at $127.99 (compared to $199.99), while the 43CX1800.1 lists at $390.49 (compared to $549.99). The 1800.1 costs roughly three times as much, which is justified only if your subwoofer can use the extra power. If you're building a modest system, the CX400.1 leaves more budget for a quality subwoofer and enclosure, which often matters more for sound than raw amplifier wattage.
Key trade-offs to weigh
- Power vs. subwoofer match: The 43CX1800.1 delivers far more power than the CX400.1. If your sub's RMS rating is below the 400.1's output, the smaller amp is the safer match; if your sub needs more than 400 watts, the 1800.1 is the better fit. Check your subwoofer's RMS rating before deciding.
- Space vs. output: The 43CX1800.1 is physically larger and may not fit in tight install locations. The CX400.1's compact size suits space-limited builds. Measure your mounting area first.
- Budget vs. headroom: The CX400.1 costs significantly less, leaving money for a better sub or enclosure. The 43CX1800.1 costs more but provides power headroom for future upgrades. Decide whether you need headroom now or later.
Product facts
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Kicker CX400.1 CX Series Subwoofer Amplifier: CX-Series mono amp with one-ohm stability and optional remote level control. It can safely run a one-ohm sub and lets you adjust bass from the dash if you add the remote.
Kicker CX400.1 CX Series Subwoofer Amplifier
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Kicker 43CX1800.1 Subwoofer Amplifier: CXA1800.1 mono amplifier built for big bass with one-ohm stability and optional remote level control. It provides much more power for high-output subs while keeping dash-adjustable bass within reach.
Kicker 43CX1800.1 Subwoofer Amplifier
Which should you choose?
Best for
- A single subwoofer with an RMS rating around 400 watts or less
- Installs where mounting space is tight
- Budget-conscious builds that prioritize subwoofer quality over amplifier power
Not for
- Subwoofers that require more than 400 watts RMS to perform well
- Listeners who want maximum bass output and plan to run at one ohm
- Builds with ample space and a higher budget for future upgrades