Christmas cut off: As the cut-off date has passed, Christmas delivery may not be guaranteed. Please select Express shipping for the best chance of delivery before Christmas.
Our team will be on holiday from Dec 22nd to Jan 15th. Please be assured that your order will be dispatched, and any inquiries will be promptly addressed upon our return. We appreciate your understanding and patience during this period.

Christmas cut off: As the cut-off date has passed, Christmas delivery may not be guaranteed. Please select Express shipping for the best chance of delivery before Christmas.

Our team will be on holiday from Dec 22nd to Jan 15th. Please be assured that your order will be dispatched, and any inquiries will be promptly addressed upon our return. We appreciate your understanding and patience during this period.

Currently Browsing

Infinity REF-551A Reference 550W Mono Subwoofer Amplifier

UPC: 050667370916 SKU: REF-551A
Infinity REF-551A Reference 550W Mono Subwoofer AmplifierInfinity REF-551A Reference 550W Mono Subwoofer AmplifierInfinity REF-551A Reference 550W Mono Subwoofer Amplifier
$399
$399$316.85
Shipping Calculator
  • Standard to Metro (4-10 biz days)
  • Express to Metro (1-4 biz days)
  • Standard to Non-metro (10-20 biz days)
  • Express to Non-metro (2-6 biz days)
  • Pickup (Same or next biz day)
  • Longer ETA applies to NT, WA, NZ & US locations.
  • The above time frames are estimates only. The actual delivery time is dependent on the shipping location, shipper's processing capacity and other unforeseeable factors i.e. natural disasters, accidents etc. We cannot be held responsible for any courier-related delivery delays.
  • 12 Month Australian Warranty
  • Brand: Infinity
  • Availability:Out of Stock
  • Model: REF-551A
  • 9 Reviews
 Sold Out 

Be notified when this product is back in stock

We will not send you any other emails or add you to our newsletter. You will only be emailed about this product.


Pickup at our Deer Park VIC warehouse. Schedule Pickup »
schedule pickup warehouse

High-Performance Mono Subwoofer Amplifier

  • High & low-level inputs
  • Compact footprint
  • HALOsonic mixing input
  • Variable crossovers & bass boost
  • ADAS input with Channel assignment
  • Fuse rating 30A x 2
  • Class-D amp technology
  • Pre-amp and speaker-level inputs

* DISCLAIMER: Design, features and specifications subject to change without notice. Some features in videos on the Internet may not be available on all models, please contact us for the TECHNICAL SPECIFICATIONS for a complete list of features by model. This feature list is for reference only, please contact us to verify features and functionality.
Boom boom boom boom

I like it a lot. Paired it with a down-firing Kicker 12" with passive radiator. Sound is so good. Plenty of bass for me.
Orange Cat Compu, 2020-12-17 on Amazon



Probably the best budget amplifier on the market

Excellent amplifier. This and the JBL club 5501 both use the same Harman kardon amplifier circuitry. I'm sure there's another much higher end model that uses the same circuit board, because both amplifiers have features that are not listed anywhere in their literature and which both JBL and infinity will deny they have. Most notably the reference 551 a and the club 5501 are capable of sensing an audio signal to turn on and off instead of using a dedicated remote line. they are also capable of putting out quite a bit more power than their rated for which is pretty rare. At $140 I don't think you can buy a better amplifier. Certainly not new.
Envy, 2019-05-30 on Amazon



Powerful, compact amplifier

This thing can pump out the juice, that's for sure. Easily powers my 2 12" MTX subwoofers, and for the price you can't really beat this amp.
Tommy G, 2019-05-01 on Amazon



REF0551A

This is a great little amp for installing a single sub. I installed mine in a 2018 Honda accord to help make up for the lack of bass. In addition to this amp I installed a 10" Infinity sub. Together they produce all the bass I was looking for and need in my car. Highly recommended!!
Brucea2, 2019-01-07 on Amazon



Fantastic audio

Amazing Amp. Perfect at what it does.Finally got my Infinity 120.9w Kappa sub hooked up to this. This combo is a beast. Won't win any SPL contests, but you can't beat the sound quality
Justin Peltier, 2017-01-13 on Amazon



Five Stars

Very good product
Amazon Customer, 2016-10-03 on Amazon



Feel the bias

Looks great and works great with 2 10’ punch subs
Jamoose , 2018-01-25 on Amazon



ok amp

nice looking
AudioPhile, 2019-03-20 on Amazon



Short lived performance

Mine only lasted a month...
Thomas, 2019-02-24 on Amazon





Cart