It's good to have an AirHead around, but a Total AirHead is even better. But best of all is a BitHead.

I am talking about the nifty portable headphone amplifiers made by the self-proclaimed "obsessed headphone geeks" at HeadRoom in scenic downtown Bozeman, Montana. I have been itching for an opportunity to tell you about them, and now that they have made amps -- the BitHead series -- designed for computer users, I have a good excuse to do so.

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Two questions, no doubt, have just popped into your mind:

• What's a "headphone amplifier"?
   
• Did you just say "Bozeman, Montana"?

Dealing with the second first: Yes to Bozeman. Tyll Hertsens, the company's founder president, and CEO, developed his headphone fixation while a Los Angeles-based businessman who was always on the road and in need of a little traveling music. Montana, as you know, is where LA refugees go when they want to get as far removed from the Southland lifestyle as possible.

As to amplifiers, that takes a little more, ahem, amplification. I first called upon the HeadRoom folks several years ago when consumer electronics makers started getting chintzy and stopped putting headphone jacks into TVs, VCRs, CD players, even receivers and stereo amps. HeadRoom had a little battery-powered amplifier called an "AirHead" that, with the right cable, you could connect to RCA audio outputs of your equipment and get a nice clean feed for your headphones.

It turns out, however, that even if you do have a headphone jack, there are good reasons for a special amp for your cans.

For one thing, audio-video components are typically designed to drive speakers, and headphone jacks are an afterthought using secondary circuits that don't have the full sound quality of the main outputs. As a look at HeadRoom's price list will tell you, high-fidelity headphone circuitry isn't cheap and would drive the cost of moderate-price stereo components into the high-end range.

Second, built-in jacks usually are underpowered. A common misconception in audio is that more power is relevant only if you are looking for louder volume. Not so. Higher power also helps improve the fidelity of reproduction. Headphones are just small speakers, after all, and like any speaker, the higher-end models require more power to operate.

Finally, there is the matter of what the HeadRoom calls "blobs in your head." What it is, is exaggerated separation between the left and right stereo channels, which recording engineers use to create the proverbial "room-filling sound." When you listen through speakers, both ears listen to both speakers and you get the sense of a performance spread out across your room. Not true with headphones: the left ear gets the left channel and only the left channel; ditto for the right. This can be fun for awhile, but over time the sensation of having separated rather than blended sound gets old and listening is less pleasant. A duet, for example, sounds like two people giving a different performance in each of your ears rather than a duet.

HeadRoom's amps have audio processing circuitry built into them that cross-feeds the channels, with a time delay to simulate the way your left ear hears the output from the right speaker a fraction of a second after your right ear does. It's not the easiest thing in the world to explain, but the bottom line is that it makes headphone listening match up with the music. If you really want blobs in your head, the processor can be shut off.

You can spend nearly $4,000 on a HeadRoom headphone amplifier. But you would need really good ears and a really big wallet to justify that. The bulk of their products are in the $250-$1,000 range and are intended to complement high-end audio systems by bringing the sound you get from headphones up to par with what you are hearing from your speakers.

However, comma... That's not the subject matter here; the AirHead/BitHead line is.

That first generation AirHead design that introduced me to the HeadRoom later got a companion unit with upgraded components, the Total AirHead, and then both were mildly revised over the years (changing, for example, to AAA batteries from AAs). Then at the end of last year, the line got a total overhaul.

The electronics were massaged, the controls improved, and there now are jacks for two headphones instead of just one. The design is a flat plastic rectangle, about the size of an Altoids tin. Well, technically, it's not a rectangle but an a octagon as the corners have been flattened off and that's where the inputs and outputs are placed. A rubber panel on the top of the unit covers the batteries (four AAAs) and also serves as a skid-resistant grip.

Shortly after the launch of the new line, the company added the BitHead, a welcome addition. It's the same unit except that the left rear corner has a mini-USB port (usually used for cameras) instead of the AirHead's input for an A/C power adapter. Using the supplied cable, you plug into one of your computer's USB port and the PC will install it as one of its audio devices. A nice touch is that the necessary driver software is included in the BitHead's electronics, so there is no CD to install.

It works both in Windows and the Mac. In my testing, installation was easy. However, both the Windows and Mac computers were inconsistent about whether they would let the BitHead automatically override the system's sound card as the active audio device. Usually it worked, but sometimes a trip to the Windows Control Panel or Mac System Preferences was necessary to make the change manually. You also need to turn up your system's volume level -- around 80-90 percent of maximum worked for me -- to give the BitHead enough input.

As with all USB sound devices, the idea is to bypass the PC's electronic system noise that compromises audio quality. Through headphones, this becomes all the more evident; hence, simply plugging an AirHead into your sound card output is not an adequate solution. The BitHead also is a natural fit for notebook users on the road. Lugging high output speaker systems around while traveling is not an option. A BitHead and good headphones lets you crank up the volume while not inspiring the rest of the passengers on the airplane to go look for a Sky Marshal to haul you away.

For additional stylishness, you now can get BitHead and AirHeads with a clear case instead of the original basic black. The clear models show off the internal components and look particularly cool in computer applications.

On battery power the BitHead will function as an amp for your iPod or other portable music players. I think most users will find they will get more use from the BitHead than an AirHead. The price premium is $50 but you get the dual PC and portable audio capabilities. Giving up the option of A/C power is not a problem since the battery life is really good. HeadRoom says 40 hours and my experience bears that out.

Bear in mind that an AirHead or BitHead is about the same size as an iPod (it's a little smaller than competing players). While the HeadRoom sells bags just for the purpose of carrying both, I never have been sold on the idea of schlepping both around that way in everyday use. It defeats the purpose of the of the iPod's miniaturization. The better use is to think of this as the headphone equivalent of plugging your iPod into your stereo system and use it for serious listening at home or on a long trip.

And for sure, notebook computers and a BitHead are a perfect match.

(c) 2004 Al Gordon.

In addition to his computer interests, Al Gordon is a principal in the Boston-area strategic consulting firm, Mary Fifield Associates, www.maryfifieldassociates.com

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You can reach Al Gordon at:

al@tnpcnewsletter.com