BMW Audio Upgrades


Does your BMW lack audio quality?

Why Source Sounds?

Expert installation engineers

We have engineers that have been working on vehicles for more than 30 years.

We understand

We understand what its like to own a prestigious vehicle and have the upmost care when working on your vehicle.

Point of contact

Throughout the whole process, you will be appointed a certain member of staff that will run through everything with you from start to finish.

Customer service

We believe that the customer is royalty and whatever you require we strive to exceed that.

We listen

We take extreme pride in not selling you something you do not need. We listen to your requirements and offer suitable solutions.

Our reviews

Our Google reviews speak for themselves, if you have a minute we suggest your browse through them.



The two-way APBMW K4E kit creates a three-dimensional sound stage and give the musical message the essential timbre accuracy.

The 100 mm (4″) midrange is provided with a water-repellent pressed-paper cone, a material providing natural sound. It features a low resonance frequency that allows hi-pass cut-off in the 150-200 Hz range for an excellent mid-low reproduction.

The 25 mm coil and Tetolon dome tweeter features a great extension on both medium and high frequencies and is optimized for off-axis output, for an extended sound stage in the three dimensions, that amplifies the perception of reality in the car cabin.


Subwoofers have been designed with electro-acoustic parameters that maximize performance for the factory box available below the seats. The ABS plastic basket, reinforced with fiberglass, and the acoustic structure. Featuring a front magnet, provide for a minimal installation depth for a perfect compatibility with the whole range. Two 5 mm polyurethane gaskets, supplied, allow the subwoofer to fit perfectly to the box, decoupling it from vibration.

The 200 mm (8″) APBMW S subwoofers allow a “direct replacement” of the OEM speakers underneath the front seats, making the most of the factory acoustic load and generating deep and crisp low frequencies.

You can choose between S8-2 with 2 ohm impedance and S8-4 with 4 ohm impedance for improved system composition versatility. In fact, in the mid-high passive filtered system configuration, with the crossover provided, 4 of the 8-channels of the AP 8.9 bit can be configured in bridge mode delivering 130W rms to each S8-4 installed under the seat. The S8-2 can be used in a fully active, multi-amplified front system, maximizing the power of the AP 8.9 bit at 2 ohms, and employing additional 2 channels for the rear system. The Neodymium magnet used on S8-4 and S8-2 allows for greater power and control than ferrite, while maintaining the depth of installation unaltered.


The AP8.9 bit amplifier was designed by Audison R&D Department to achieve maximum sound quality in OEM Integration applications. The powerful management software proves the ability to acquire the bit Drive presets which the Audison team fine-tuned specifically for your car. Thanks to the innovative power supply stage, a power of 520 W total can be achieved in an extremely compact case. The non-amplifiable ninth channel can be used to drive a subwoofer via the mono AP1 D amplifier.

This amplifier includes the Audison bit technology that you can see in the background. This is a very sophisticated system that gives us as the specialists a unique edge on tailoring the system to your needs. This isn’t something you as the customer needs to worry about as anything you don’t understand, Source Sounds take care of this for you. 

The packages we offer

This package consists of upgrading the Mid-Range speakers in the doors with the Audison Prima K4E 4″ component kit. This also includes the Audison Prima 1″ Tweeter which would be mounted in the factory location on the A-Pillar. The crisp Audison tweeter will give you the definition on the higher frequencies you so desperately need. 

The factory underseat woofers are untouched and everything including the replacement speakers are powered from the factory headunit. This means that the new speakers we install will be getting the same quality signal that the factory speakers were receiving. 

This upgrade will improve the acoustics of the vehicle without a doubt but will not necessarily give you anymore “output” from the system (loudness / bass). This is because they are being provided with the factory headunit signal. 

This upgrade costs £419.99 Fitted. 

This package consists of everything in the “Starter” package plus an additional amplifier. 

The amplifier is the Audison Prima AP4.9bit 4 channel amplifier with 9 channels of processing. This amplifier is used to power the Audison Prima K4E 4″  component kit that we install in the front of the vehicle as well as the factory BMW under seat woofers. In addition, because this amplifier has in-built processing, this means we are able to “De-Equalise” the horrible factory stereo system. 

The doors on the vehicle are lined with Skinz soundproofing to absorb the kinetic energy that would technically be wasted inside the door. This gives the speaker the ability to play better without you hearing rattles and resonance in the doors. 

With the amplifier providing the new speakers and the factory BMW underseat woofers with a cleaner and better signal, this means that the overall performance of the audio system is considerably increased over the starter package. The acoustics of the vehicle would be dramatically improved and the bass from the underseat woofers will also be very noticeable. Do not worry, we make sure the underseat woofers are crossed off at a certain frequency to make sure we don’t damage them. 

This upgrade package costs £1339.99 fitted.

This is our highest package we offer and is recommended for anyone who is truly into their audio. 

In this upgrade the front Mid-Range speakers are changed for the Audison Prima K4E 4″ component kit, the underseat woofers are replaced with the Audison Prima S84 8″ woofer and an Audison Prima AP8.9bit amplifier is added to the system. 

The acoustics of this system are outstanding and the bass is very defined. The Audison Prima AP8.9bit is bridged into a 4 channel amplifier which greatly improves the output of each channel to produce a more powerful and cleaner signal to all the components. The Prima 4″ component kit and the Prima 8″ underseat woofers are all powered from the 8.9bit and with the processing of the amplifier, this means we can “de-equalise” the factory audio output. 

The doors on the vehicle are lined with Skinz soundproofing to absorb the kinetic energy that would technically be wasted inside the door. This gives the speaker the ability to play better without you hearing rattles and resonance in the doors. 

This system comes with a full time alignment set up and 30-60 minutes of Paul’s time sitting in the vehicle with yourself setting the vehicle up to your preferred listening method; giving you 2 different presets.

This upgrade costs £1989.99 Fitted

These are just some of the systems we offer off the shelf, a bespoke system can be designed specifically to suit your needs. Please Contact Us.

Our YouTube

We have worked on numerous amounts of BMW’s for audio upgrades, click the YouTube icon below to see what we do and how we install the equipment to your BMW.

The UK's Ultimate Car Audio, Security and Navigation Specialists, having been voted on numerous occasions by the "UK's Best Installers" by the Car Audio, Security & Navigation Industry Find out why...

I arrived to find two technicians on their lunch break busily helping a lost parcel delivery guy waylaid with items. This bode well for assessing the character of Source Sounds. A replacement head unit and the re wiring of a sub made me self concious that I was not their biggest customer. I could not have been more wrong. They squeezed my job in that very day and phoned me as soon as all was complete. I never had to repeat anything twice. Lee’s perseverance and tenacity was infectious. Several minor issues that I had tolerated previously are now history. I thoroughly recommend this company.

— Nick Kilner

The best car audio in Sheffield! Paul spent over an hour with me just talking about everything, door speakers, amps, sub woofers & these guys really know their stuff. Chris (who did the work on my car) spent ages making sure I had no rattles at all. I got a top of the range set up within my budget, head unit, amp, sub & door speakers & cannot speak highly enough for these guys, i learned loads & got a system that properly rocks. If you want car audio, go see these guys, even if just for a quick chat, you’ll see what the hype is about. 10/10

— Joe Walker

Absolutely first class customer service with some real friendly and knowledgeable guys. I had every option and product explained to me in depth and the finished product is perfect. I will be using them for years to come