The W205 C300 is available with both a "premium" audio Burmester branded audio system and a basic 4 speaker setup. The basic setup with 4 speakers has no tweeters and no center speaker on the dashboard. We were very disappointed with the sound quality of this system as it's noticeably worse than previous generations of the Mercedes C-Class. The Burmester system offered on these cars are also considerably worse than the system offered on the E-Class. In fact, the door speakers are the same whether you get the Burmester option or not. These small 3.5" speakers offer poor performance across the board and are some of the worse we've found in any "luxury" branded vehicle.
We tried to address issues with the bass, mids, and highs while keeping our customer's budget in mind. For the speakers, we went with the Optisound lineup from Vibe, a British car audio brand, that makes a factory speaker upgrade for BMW. These 4" speakers are a direct replacement for the speakers found in E series BMW and use a composite paper and wood fibre cone for excellent voice reproduction. The high quality neodymium magnets offer good power and efficiency while retaining a shallow mounting depth.
Despite the small size of these speakers, they can take up to 115W RMS which is well beyond the capability of the standard system in this C-Class. Not only that but we added the tweeter for crystal clear highs. Even though this C300 did not originally come with tweeters, there is already a grille in the corner of the door for them, making for a clean and stock-looking installation. Surprisingly, these BMW replacement speakers were almost a direct fit for the Mercedes so we had no issues with clearance or mounting.
Our customer wanted to feel more bass for the EDM tracks she listened to but didn't want to take up any trunk space to mount a full size amp and subwoofer combo. We took some measurements and found that the Kenwood KSC-SW11 fit perfectly between the seat rails on the passenger side and takes up virtually no cabin space. This is a compact powered enclosure meaning it's an all-in-one solution that has the housing, amplifier, and woofer in one neat package.
The Kenwood uses a 5"x7" woofer and has a wired remote control to control the crossover and gain levels. It has a power rating of 75W RMS which is certainly enough to produce bass you can feel since it's under the front seat. As far as compact subwoofers go, options from JVC and Alpine that feature 8" woofers produce better quality bass, but due to the size restrictions in this C300, we had to go with the Kenwood. The nice thing about these systems is that they are a simpler install as power comes from the fuse box and they have high-level inputs making it easy to add to a factory system.
To top it off, we installed the Sony XM-GS6DSP amp under the driver's seat. This amp not only pushes more power to the speakers but it cleans up the signal too with additional fine tuning by way of a digital sound processor (DSP). The DSP is tuned through a bluetooth app and offers a lot more adjustment than the standard Mercedes system with an advanced equalizer and time alignment settings.
This is also a 6-channel amplifier meaning not only are the door speakers taken care of but there are an additional 2 channels for powering a subwoofer. In the meantime we only have the signal for the subwoofer going to the Kenwood compact subwoofer but this amp does leave headroom for our customer to install a fairly powerful full size subwoofer. The bridged output of the sub channel is 600W @ 2 ohms or 350W @ 4 ohms which is certainly enough for a modest sized trunk subwoofer in this car.
For less than the cost of most factory premium audio upgrades, we were able to provide a much better all-around system. The door speakers alone made a huge difference when compared to the cheap and flimsy stock speakers that struggled to produce any real bass or treble.