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Deal.ai › Alpine › 6 Channel Car Amplifiers
Alpine
Alpine R-A90S

Alpine R-A90S

4.9· 28 ratings

Last price we saw

$699.95at SonicElectronix.com, last seen Nov 5

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Our take on the Alpine R-A90S

The Alpine R-A90S is a Class D 6-channel car amplifier rated at 900 watts total. It delivers 75 watts RMS per channel at 4 ohms, 100 watts at 2 ohms, and 200 watts bridged into two channels, so it can run a full front-stage plus sub setup from one chassis. A 50-400 Hz variable low-pass/band-pass filter and 0.03% THD at rated power round out the tuning. The best new price is $699.95 at SonicElectronix.com as of November 5, 2026, with 3 stores selling it new.

Best forUpgrading a factory system with front, rear and sub channelsBuilding an active 3-way front stage plus subwooferDrivers who want one compact amp instead of twoSQ-focused listeners on a mid-range budget
Pros
  • Six channels cover tweeters, mids and a sub from one amp
  • Class D design runs cooler and draws less current than Class AB
  • Low 0.03% THD at rated RMS power
  • Band-pass filtering lets you run midrange channels cleanly
  • Compact 12.75" x 10.75" x 2" footprint fits under seats
  • Handles 2-ohm loads unbridged and 4-ohm bridged
Cons
  • Speaker-level inputs need a separate adapter
  • 8 AWG maximum power wire is small for a 900-watt amp
  • 90A fuse rating limits how much real power you can pull
  • High-level input range tops out at 10 volts, so some factory head units need a line converter

Alpine R-A90S prices at every store

  • eBayCheck price at eBay
  • WalmartCheck price at Walmart
  • SonicElectronix.comCheck price at SonicElectronix.com

Alpine R-A90S price history

Lowest price we've seen: $699.95 on Nov 5 at SonicElectronix.com. Tracked across 1 store since Nov 5.

What reviewers say

  • 4.9 / 528 ratings

Owners rate the R-A90S very highly, 4.9 out of 5 from 28 ratings, and most praise its clean output and flexible channel layout. Complaints are few and mostly about install details.

What people mention
  • Sound qualityPraisedOwners describe clean, detailed output with low noise.
  • Channel flexibilityPraisedSix channels and band-pass filtering let buyers run active front stages plus a sub.
  • Heat and sizePraisedThe Class D chassis runs cool and fits under seats.
  • InstallationMixedWiring is straightforward, but the 8 AWG input limit and optional speaker-level adapter add friction.
  • ValuePraisedBuyers see it as a lot of clean power for the price.

About the Alpine R-A90S

Experience your music in Hi-Res with the versatile R-A90S 6-Channel Amplifier for hair-raising details that puts you in the center of the performance.

Specifications

Total Power Output
900 watts
High Level
0.5 - 10 volts
Total Harmonic Distortion (THD)
1%
Signal To Noise Ratio
85 dB
Variable Low-Pass / Band-Pass Filter
50 - 400 Hz
Fuse Rating
90A
Dimensions
12.75" L x 10.75" W x 2" H

Questions and answers

Is the Alpine R-A90S worth it?
For a one-amp six-channel build it is a strong pick: 900 watts total, low distortion and a small chassis. At $699.95 at SonicElectronix.com as of November 5, 2026, it sits near the middle of its recent range.
How much power does it really make?
Alpine rates it at 75 watts RMS x 4 at 4 ohms, 100 watts x 4 at 2 ohms, and 200 watts x 2 bridged. The 900-watt figure is the total peak rating, not per-channel RMS.
Can I keep my factory head unit?
Yes, but speaker-level inputs need an optional adapter, and the high-level input tops out at 10 volts. Many factory systems will also want a line output converter.
What wire and fuse does it need?
It takes up to 8 AWG power wire and carries a 90A fuse. For a full 900-watt build, plan your wiring and charging system around that limit.
How does it compare with a 5-channel amp?
The sixth channel lets you run a fully active front stage (tweeter, mid, midbass) plus rear fill and a sub. A 5-channel amp forces passive crossovers on the front speakers.
When is it cheapest?
Prices vary by store; 3 stores list it new, and the best price seen is $699.95 at SonicElectronix.com as of November 5, 2026. Check the price history before buying.
What do buyers say about the Alpine R-A90S?
Rated 4.9 out of 5 from 28 ratings.
Where can I buy the Alpine R-A90S?
3 stores we checked sell it, including eBay, Walmart, SonicElectronix.com.

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RMS Power @ 4 Ohms
75 watts x 4 channel
RMS Power @ 2 Ohms
100 watts x 4 channel
Bridged RMS Power
200 watts x 2 channel
Amplifier Class
D
Number Of Channels
6-Channel
Maximum Input Gauge Size
8 AWG
Minimum Impedance Unbridged
2 ohm
Minimum Impedance Bridged
4 ohms
THD At Rated RMS Power
0.03%
Speaker Level Inputs
Optional (Requires Accessory Adapter)
color
BlackSource