HEADPHONE OUTPUTS: WHAT’S WRONG?
Many amplifiers, receivers and home theatre receivers have a nice 6.35mm diameter hole on the front. It is designed, of course, for headphone listening. And it may deliver a nice signal to your headphones… or it may not.
Indeed, many headphone outputs deliver a potentially poor signal… and have for very many years. And the reason is not what we in the high-fidelity community regard as the traditional culprits—mere integrated circuits rather than proper discrete transistor-based amplifier stages. Indeed, as we’ll see, IC-based headphone amps are typically better than many headphone outputs built into otherwise high-quality gear.
No, the culprit is usually the addition of resistors in line with the headphone output.
WHY DO THEY DO THAT?
What’s the value of these resistors, you may ask, and why would they put them in line with the headphone output in the first place?
Well, first, some measured examples. And remember, these are all fine piece of equipment in every other respect. It’s just that they happened to pass through my office over the past few months. Here are all five that I measured:
› 99Ω — Yamaha Aven99tage RX-A3080 Home Theatre Receiver.
› 325Ω — Pioneer VSX-LX303 AV Receiver.
› 465Ω — NAD
