Car audio used to be pretty straightforward. If you cared at all about decent sound quality -- and getting the most for your money -- you drove straight to a stereo shop shortly after buying a new car. They ripped out the second-rate stock stereo components and replaced them with superior aftermarket gear that was also a much better value than even most “premium” systems from the automaker. Or if you knew a bit about cars and electronics and were handy with tools, you did it yourself on a Saturday afternoon in your driveway.

Now, it’s not so simple. Stereo systems in most vehicles are tied to other electronics in the car: a navigation system, Bluetooth hands-free for a phone and sometimes even climate controls. And cars have become so sophisticated that many owners are reluctant even to let a professional installer tap into sensitive stock electronics, much less choose the do-it-yourself route.

One more nail in the coffin of aftermarket stereo is that automakers have finally gotten serious about providing good audio. (And some of the best-known aftermarket names have been playing both side of the fence for years by supplying the branded systems for new cars.) Not only has the quality of stock stereo systems improved across the board, but they’ve also become a better value compared with starting from scratch with an aftermarket system.

While that’s bad news for the aftermarket, it’s a big advantage for consumers. On the flip side, it can be more difficult to decide whether you should pay extra for a premium name-brand system instead of going with the standard setup. Not every system with a fancy name on the speakers or head unit is worth the extra dough. In fact, I’ve heard many that are not, plus some no-name systems that sound great.

But whether you’re a golden-eared audiophile or don’t know a woofer from a tweeter, there’s a simple, surefire method for making sure that a system meets your sonic expectations. The key is to test a system using music you like and crank it up (or down) as much as you like. Some of the high-end audio brands supply their own “demo” disc to show off a stereo; those, of course, sound great on their systems. Don’t use those. Instead, use music you’re familiar with and have heard a hundred times or more – whether it’s Dr. Dre or Debussy.

Make sure to listen at different volumes, at different speeds and on different road surfaces, if possible. Also sample any signal processing that’s available. To my ears, most of the surround-sound schemes available are pretty gimmicky, and I prefer to listen in plain ol’ stereo. Just make sure you can switch off any signal processing. (You usually can.)

Beyond the sound, you’ll want to find out if the audio system’s controls are easy to use, especially at speed. This, too, used to be much simpler: You had volume, track skip forward/back, radio station presets and a few tone controls. Today’s audio systems can control an iPod or USB drive loaded with digital tunes, download music to a hard drive and even access Pandora Internet radio. Make sure that the interface is straightforward and easy to operate on the fly. Also check to see that the display is easy to read, particularly in bright sunlight. And if it’s a touch-screen, see how it responds to inputs and its response time.

Find out all of this before you buy -- not a couple of months down the road, when you’ll feel like you’ve been burned. Then you’ll probably want rip out the system and start over with aftermarket components. And did I mention how difficult that can be?

Doug Newcomb has been covering car technology for over 20 years for outlets ranging from Rolling Stone to Edmunds.com. In 2008, he published his first book, "Car Audio for Dummies" (Wiley). He lives and drives in Hood River, Ore., with his wife and two kids, who share his passion for cars and car technology, especially driving and listening to music.