[victorle]

I have an old stereo (bought 8 years ago).
Can I use it as a headphone amp by connecting
a headphone to the speakers' connectors?

(It is stated in the manual that the stereo should
connect to speakers with a nominal impedance
ranging from 8 to 16 ohms, what happen if I
connect a 100 ohm or higher headphone to it?)

 

[Tomo]

Hello,

You can potentially blow your headphones. In any case, speaker amplifiers have low noise and distortion tolerances. So it is better to get real headphone jack or headphone amp.

Tomo

 

[zoboomofo]

Tomo is so pleasant about warning you of a potential headphone crisis.

 

[thomas]

Unless you really need the high volumes levels, then i doubt a speaker amp would be better than the built in amps in your equipment.

Most of us use headphone amps to improve sound quality, rather than getting louder volumes...A dedicated headphone amp will sound MUCH cleaner than just about any poweramp.

If you really want to to this, go to headwize.com, and look in the FAQ section, which will give you instructions on building an attenuator to reduce the power of the speaker output to headphone levels. If you don't put a resistor in between the poweramp and the headphone, the amp will put out enough power to destroy your headphones.

 

[Mike C]

I have an old stereo (bought 8 years ago).
Can I use it as a headphone amp by connecting
a headphone to the speakers' connectors?

(It is stated in the manual that the stereo should
connect to speakers with a nominal impedance
ranging from 8 to 16 ohms, what happen if I
connect a 100 ohm or higher headphone to it?)

Don't do that, but you might try this.
Connect a 2 ohm and 6 ohm resistor in series, and connect the 2 ohm to the amp neg or earth speaker output and the 6 ohm to the amp positive or live speaker output. Connect a headphone socket neg or earth to the amp neg or earth, connect the positive or live to the junction of the 2 ohm and 6 ohm resistors.
The resistors must be of adequate power rating, say 5 watt but check they don't get very hot.
That way the amp sees an 8 ohm load and the signal to the phones is reasonably attenuated. If it works OK, try different resistors (adding up to 8 ohms) to get a suitable volume range.
When I first got into headphones I tried various things with spare valve amps and preamps, results were generally poor to awful but the above was reasonable. For a few pounds/dollars it may be worth trying. I suggest Kiwame 5 watt resistors.
But even my least good diy valve headphone amp was a whole lot better.