There are five accessories that come up again and again when people talk about getting the best audio from their iPods. We've collected them in this slide show as a kind of iPod audiophile 101.
Before we get started, though, let's talk about the iPod itself. If you're shopping for a new iPod or you've got an older iPod and you're wondering about upgrading, bear in mind how much storage you'll need. Ripping CDs as audiophile-worthy Apple Lossless files or high bit-rate MP3 or AAC files, eats up a lot more room than your average 128kbps MP3.
High-capacity hard-drive MP3 players aren't as fashionable as the slimmer, lighter Flash-based MP3 players we see these days, but you can't beat them when it comes to storage. The 120GB iPod Classic is probably your best option right now if you're shopping for an iPod to hold all those high-resolution files.
If you do nothing else on your journey toward iPod audio nirvana, throw out those earbuds that came bundled with your iPod and invest in a serious upgrade. No other step outlined here offers a bigger bang for your buck than a quality pair of sound-isolating in-ear headphones.
In fact, hearing the difference a good pair of in-ear headphones can make on your music is usually where iPod users first get bitten by the audiophile bug. The difference is often so dramatic, that you begin wondering what else you're missing out on.
Now, you can go nuts and shell out $400 or more on a premium pair of multi-driver earphones, but if you're just upgrading from the stock iPod earbuds, a little money can go a long way. Apple's own in-ear headphones are one of the best values we've seen under $100. If you can spare the extra money, there are dozens of "flavor of the month" high-end earphones people swear by, but we typically recommend the Shure SE310 and Etymotic HF5, for people shopping in the $200 range.
After ditching the iPod's stock earbuds, the next weakest link in the audio chain is the tiny amp powering the iPod's headphone jack. The headphone amp built into your iPod isn't bad, per se, but ultimately it's engineered to conserve battery life and avoid lawsuits from idiots who crank the volume too high.
If you've invested in a "real" pair of headphones or earphones, it follows that you should hear them through a "real" headphone amp (can you see the slippery slope ahead of you yet?). Headphone amps in general aren't hard to come by, but only a few boutique companies make portable amps. One of the smallest (and cheapest) is made by Fiio, but the most well-known is the BitHead by Headroom.
If you're feeling crafty, Systm has a great video tutorial on how to make your own headphone amp from scratch.
OK, so if you're going to get snobby about the way the iPod's internal headphone amp colors the sound quality of your music, how are you supposed to get audio out of your iPod? The answer lies in your iPod's dock connector. Of the 30 pins used in Apple's iPod dock output, two of them are used to send out line-level audio, unsullied by the iPod's headphone amplification stage.
To get at the iPod's hidden line-out you'll need to buy an adapter like the SendStation PocketDock Line Out. It's going to add a little bulk to your iPod, but hey, you've already got a headphone amp strapped to the thing, right?
Now, the line-out signal from your iPod sounds pretty dull without a quality amp to run it through, so if you're going to the trouble of adapting your iPod for a line output, you'll want an external headphone to make the effort worthwhile. That said, you don't have to use the iPod's line out to enjoy the benefits of a good headphone amp.
The sound-isolating in-ear headphones you bought in step one are great for listening to your iPod when you're out and about. When you want a personal listening experience at home, however, full-size headphones are the way to go.
Chalk it up to the physics of headphones' larger speaker drivers, the psycho-acoustic differences of sound produced outside your skull, rather than within it, or the comfort of a padded headband versus shoving a piece of plastic into your ear.
People get very passionate about their headphones, which makes recommending a pair like opening a can of worms. My current faves, though, are the Ultrasone HFI-2200. CNET's resident Audiophiliac Steve Guttenberg has a list of his top three favorites, as well.
Finally, one surefire way to restore some analog warmth to digital audio is by running it through a vacuum tube preamp. Tube technology is fragile, fickle, and sometimes hot enough to heat a room, but there's a certain magic in the way vacuum tubes handle audio that has preserved the technology into the 21st century.
It's easy to find standalone tube preamps offered by high-end stereo manufacturers, but if you want a solution made just for the iPod, CNET UK's Nate Lanxon just won't shut up about the Fatman iTube 452, which includes an integrated iPod dock and two 45W amplifier output channels.