Skip to content

Adastra A4-PLUS - 4 Channel Stereo PA Amplifier, 4 x 300W, 4 Ohm with Bluetooth

by Adastra
Original price £299.00 (inc. VAT) - Original price £299.00 (inc. VAT)
Original price £299.00 (inc. VAT)
£299.00 (inc. VAT)
£299.00 (inc. VAT) - £299.00 (inc. VAT)
Current price £299.00 (inc. VAT)
SKU 953.434

Adastra A4 PLUS - 4 Channel Stereo PA Amplifier


NEW: Adastra A4-PLUS 4 x 300W Stereo Power Amplifier with Bluetooth, USB & FM Radio. Perfect for driving foreground PA Speakers in bars & gyms. 

The Adastra A4-PLUS expands upon the incredible success of the A4 - by far one of our most popular commercial amplifiers. While the A4 remains an ideal choice for most background music installations, the A4-PLUS is specially designed for more demanding applications that need to run at a higher volume for longer periods of time, such as: 

  • Gyms and Fitness Studios
  • Late Night Bars & Pubs
  • Large Halls & Community Centres
  • Exhibitions & Conference Suites

The A4-PLUS offers a 4 x 300W power output, representing a 50% increase in power over the standard A4. This means the amplifier can be driven at higher volumes/power without distortion resulting in better sound quality.

Just like the A4, Channels 1/2 & 3/4 function as two zones, each with their own EQ control, and source selection meaning different audio sources can be played on each pair of channels. With each channel operating at a minimum of 4 ohms, the A4 PLUS is highly compatible with a large variety of low-impedance speakers. 

Adastra A4-PLUS - 4 Channel Stereo PA Amplifier, 4 x 300W, 4 Ohm with Bluetooth

There are 3x stereo inputs, 2x RCA and an L & R 1/4" (6.35mm) Jack that allow for a direct connection of external audio sources such as laptops, CD players & TV's, as well as 2 x Mono 1/4" (6.3mm) Jack microphone inputs. Mic input 1 features a 'Talk Over' function that overrides all of the other inputs great for dance instructors, pub quizzes, karaoke & general public address.

There is also a stereo RCA line out, which can be used to expand the system as this will allow you to send the input source to another amplifier, or compatible active sub.

An inbuilt media player section offers playback of MP3 audio tracks from a USB drive or SD card and also has a Bluetooth receiver and FM radio tuner.

The A4-PLUS remains a tremendous choice for everyday background music systems, but for jobs where extra power and headroom are required, you just can't go wrong with the A4 PLUS.

Adastra A4-PLUS Key Features:

  • Independent stereo playback to 2 separate zones
  • Media player with USB/SD playback
  • FM radio tuner with external aerial connection
  • Bluetooth connectivity built-in 
  • 19" Rack mountable (ears supplied)
Read our blog post about the best amp for restaurants

See SPECIFICATION tab for technical specs



  • Power supply: 230Vac, 50Hz (IEC)
  • Fuse: T6.3A, 250V
  • Output power RMS @ 4 Ohms: 4 x 300W
  • Output power RMS @ 8 Ohms: 4 x 150W
  • Amplifier construction: Class D
  • Dynamic Range: 92dB
  • Frequency response: 20Hz - 20kHz ±0.5dB
  • Input impedance: 20k Ohms (balanced), 10k Ohms (unbalanced)
  • Microphone inputs: 2 x 6.3mm jack (mono)
  • Line inputs Line 1: L+R (6.3mm jack/RCA), Line 2: L+R (RCA)
  • Auxiliary input: 3.5mm stereo jack
  • Audio source: USB/SD mp3 playback, FM tuner, BT receiver
  • Input controls: Aux, Media, Line1, Line2, Mic1, Mic2, Talkover
  • Line output: 4 x RCA
  • Antenna connection: F type (FM tuner)
  • Bluetooth Version: 2.3
  • Output controls: 2 x source select, 2x Bass, 2x Treble, Ch1, Ch2, Ch3, Ch4
  • Dimensions: 482 x 260 x 88mm
  • Weight: 7.13kg

Download the A4 Plus Datasheet HERE >

Sale now on at Audio Volt

60% Off Lithe Audio Garden Rock Speakers

Pay in 3 payments with Klarna at Audio Volt
PAY IN 3 WITH Klarna

18+, T&C apply, Credit subject to status

Free UK Delivery on orders over £79.00 at Audio Volt

On orders over £79.00

Fast next day delivery available at Audio Volt

Next day tracked £9.95

Compare products

{"one"=>"Select 2 or 3 items to compare", "other"=>"{{ count }} of 3 items selected"}

Select first item to compare

Select second item to compare

Select third item to compare