Adastra A4 PLUS 4 Ch 4x 300W PA Amplifierwith Bluetooth

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. 

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.

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

Digital Downloads (buying software)

All software marked as "serial download" or "digital download" will be delivered via email within normal office hours.

Simply add the software to the basket and at the delivery stage in the checkout please select "Digital Download - Software by email" as your delivery method

Delivery Charges (Main Products)

The cutoff for same-day dispatch is 3:30pm but can vary at busier times such as Christmas.

All orders over £99.00 will be delivered free via our standard delivery 2-3 days (UK Mainland)

If you need your item faster we also offer a Priority Tracked service at £3.99 (1-2 days) or Next Day Tracked £6.99

(please ensure you add a mobile number to your order for tracking)

Saturday delivery is available when ordered before 2pm (Mon-Fri)

All orders below £99.00 will start as low as £2.99 depending upon weight and qty(s) (UK Mainland) 

All Delivery options will be available at the delivery stage in the checkout

EU Delivery Times

Non UK Mainland Addresses please allow 1-3 Days
Delivery To Belgium / France / Germany please allow 3-4 Days
Music PC Systems - Please allow 5-7 Working Days build time (UK) 7-14 (Rest of the World)

French - Pour la Livraison s'il vous plaît permet en France 2-4 Jours
German - Für Lieferung Nach Deutschland erlaubt bitte 2-4 Tage

Delivery Notes
On delivery, you must inspect the goods carefully for damage as Inta Audio is unable to accept responsibility for damage in transit, shortage of delivery or loss of products unless the customer advises Inta Audio of such within three working days from the date of delivery.

Returns Policy

We ask that you follow these guidelines to help us process your return as quickly and efficiently as possible:

1. Please keep your order reference to hand. This confirms your original order and gives us the necessary details to authorise the product’s return.

2. Contact our Customer Services Team on 02476 369898 (or e-mail cs@inta-audio.com). We will then send you an RMA number and returns form which needs to be completed and sent back with the returned item(s).

3. (If the order has been unpacked) re-package it to ensure that it is being returned in its original condition. Please make sure all items relating to the product are returned, including manuals and cables.

4. When returning an item please obtain a ‘proof of postage’ receipt from the Courier.


Returned items must be mailed within 10 days of when the RMA Number has been issued. Items received with a post date 30 days after your requested return will NOT be eligible for refund.

Please note: Our returns policy is quite straightforward but there are a number of conditions that we ask our customers to comply with before applying:

1. It is your responsibility to request a return. If you don’t tell us you want to make a return, we don’t know. Once you do tell us, we will do everything we can to action it.

2. If you have not requested a return within 28 days of receiving an order, we will have assumed that you are intending to keep it and we will not authorise a return.

3. We always refund the payment according to how the original purchase was made and aim to do so within 72hrs of the return being received by us.

4. Returned goods are liable for a restocking fee of 15% towards handling and repackaging if the order is not returned in its original, unopened packaging. This charge will be subject to our inspection of the returned goods.

5. Delivery charges will not be refunded unless the delivered goods are faulty.

6. Replacement products are dispatched immediately after the returned goods have been received and accepted by Inta Audio.

7. Items that develop a fault within 30 days of delivery are eligible for a replacement or a refund. Delivery costs are also reimbursed for faulty items. Please contact our Customer Services Team on 02476 369898 if you believe your item has developed a fault.

Finally, please remember that notifying us of your intention to apply for a return, saving the delivery paperwork and keeping the order in its original packaging will help both you and Inta Audio to process the return quickly.

If you have any questions about our Returns policy please telephone us on 02476 369898 or email us at cs@inta-audio.com.