How can I spruce up my subpar stock stereo? (Roadside Assistance)

There are quite a few reasons why one would want to remove a stock stereo system from a car. Like most things with moving parts -- in this case, speakers -- components wear out, which results in degradation of sound quality over time. Sometimes, a nearly new stock stereo just isn't loud enough or clear enough for the driver's tastes and needs a good overhaul.

That's why in this week's Roadside Assistance, I'll be helping two readers replace the worn, outdated, and underpowered components of their stock stereo systems and avoid some of the pitfalls that litter the pathway to better sound.

Can removing a factory receiver affect other vehicle systems?

The short answer is yes. In some cars, particularly newer models, yanking out the OEM headunit can wreak all kinds of havoc on your car's auxiliary functions. More and more, automakers are combining the electronics that run the climate system, security system, door chimes, and the like into the chassis of the OEM stereo. In these cases, removing the stereo can cause any or all of these systems to cease operating unless you replace or relocate the stock unit or install some sort of OEM integration kit to replicate these functions.

However, in all of my research, I've seen no indicator that the 2004 Avalon is one of these vehicles. You should be safe to remove the unit without disabling your climate control system. If you'd like, you could test this out by simply temporarily disconnecting the stereo and checking to see if anything stops working. Odds are that you'll be good to go, but just in case, be sure to locate the security code to your stock system before you pull any connections. If memory serves, Toyotas of this vintage required a six-digit numeric code to reactivate the radio after removal. You don't want to find yourself locked out of the stereo system in the event that something goes wrong and you end up having to reinstall the OEM unit.

If you find that your car functions fine without the stereo in place, simply pick up an aftermarket stereo bracket and wire harness, chose a replacement head unit, and have it installed. You can find help with choosing the right unit for your needs by checking out last week's column.

As far as replacing your rotted out subwoofer, pay very close attention to this next question.

How can I beef up my gutless OEM stereo?

I find it interesting that you think the Accord's stereo is gutless. When CNET editor Wayne Cunningham tested that very system in late 2010, he praised its audio quality, stating that "the 270-watt amp wasn't powerful enough to really kick up a lot of volume, but it did help refine the audio quality." Hmm... now that I look back, it seems that even Wayne could have used a bit more kick. All right, let's get you set up with a bit more power.

The first thing you'll want to do is decide on your budget, which will be the biggest determining factor in how far you take this upgrade, and exactly how you'd like to improve the sound. Do you just want more bass or an overall louder and clearer system?

If you're on a limited budget and it's just more bassy bump and thump that you're after, you may be able to make due with a simple powered subwoofer upgrade. To pull this off, you'll ideally only need two pieces of new hardware. The first bit is an aftermarket amp. Since you'll only be powering one speaker (the subwoofer), you can save money by choosing a single-channel (or mono) amplifier, but don't go too cheap with some $50 knock-off eBay unit: the amp is the engine that's driving your audio. Look for an amp with a built-in crossover (to keep your new sub from distorting by trying to reproduce high frequency audio) and a high-level input (which allows you to plug your car's speaker level inputs directly into the amp). If you can't find a unit with a high-level input, then you'll also need a line-out converter (or LOC) to convert your stereo's amplified speaker level output to a line (or preamplified) level that your amp can use. Note: there are many audiophiles who will no doubt thumb their noses at using high-level inputs or an LOC, but I'm going for quick, dirty, and cheap here.

The other bit that you'll need is the subwoofer itself. If your amp is a bass engine, the subwoofer is where the rubber meets the road, so don't cheap out here either. Look for an established brand like Rockford-Fosgate, Alpine, or JBL. The Accord's stock sub is 8 inches in diameter and 5 inches deep, so look for something that fits those dimensions if you're looking to use the stock location. If you're going bigger, you'll need to install some sort of sub enclosure in your trunk to house the larger speaker. Most importantly, make sure your chosen subwoofer's power rating isn't lower than the output of your amp or you'll end up distorting your audio or, worse, blowing out your new sub.

I'd budget about $300 for a nice 350-watt amp and $160 more for a matching 8-inch subwoofer. (Sticking with the same brand and series for your speaker and amp can make power matching easier.) Be sure to keep an eye out for deals; it's easy to find car stereo equipment for well below MSRP if you shop around. Factor in an additional $30 for the cables you'll need to connect everything and about $100 more for the installation. With the example I've given, you're looking at around $600 when all is said and done, but you could shave hundreds off of that price by finding your parts on sale, choosing a different brand, or cutting a deal with the installer.

If you've got a bigger budget and want a more balanced system, you'll want to look at upgrading the rest of your speakers to match your new subwoofer. The rules here are mostly the same, only there's more hardware involved. Rather than just purchasing a mono amp, you'll also want a four-channel unit that can power your midrange and high-range speakers. (Although, a sufficiently powerful five or six-channel amp could do the work of both.) Obviously, you'll also need to invest in more speakers. Your local 12-volt shop can help you with sizes and adapters, but again you'll want to match the power ratings of the speakers with the output of your chosen amp.

You've got a lot of flexibility with your pricing here, depending on the component you chose. For example, I could go with something like Rockford Fosgate's Punch P1000X5D amp ($700), which can drive four full-range speaker channels with 75 continuous watts each with 200-watts left over to power a subwoofer. That amp can be matched with a Punch 8-inch shallow subwoofer ($190) and a full complement of Prime speakers: 6.5-inch component speaker sets up front (which separate the tweeter from the midrange for more flexible staging) and 6.5-inch coaxial drivers out back (which combine the tweeter and midrange into one compact package) should run you about $160. Again, sticking with the same brand takes a lot of the guesswork out of component matching. Factor in the wires and cables, speaker brackets, and installation, and you're looking at a hugely loud 500-watt system for about $1,300. Still got money to burn? Toss in a digital signal processor (DSP) like the JBL MS-8 (which can be found for $500 these days) to automatically optimize your audio quality -- it's money well spent.

Of course, your ideal system probably lives somewhere between those extremes. The great thing about car audio is that it's scalable and you don't have to do all of your upgrades all at once. You could first add a powered subwoofer and see if it adds enough extra noise to meet your needs. If not, you can always upgrade the rest of the speakers and add a second amp to drive them later. A third round of upgrades could include your DSP. You don't have to drop thousands of bucks all at one time.

Finally, the most important bit is finding a local 12-volt installer that you can trust with your precious wheels and who will give you the best price on parts and labor. Be sure to make full use of services like Yelp or a local car enthusiasts club to help narrow down your choices. Best of luck to you!

CNET Roadside Assistance is an reader Q&A column where I, Car Tech editor Antuan Goodwin, answer your automotive and car technology related questions. If you have a burning car technology question or just need something explained, send me an e-mail at cartech at cnet dot com. Put "Roadside Assistance" in the subject header and you might just see your question answered right here on CNET! You can also find me on Twitter and send me your questions there. Just follow @antgoo.