Is Amplifying Low-End Sources Worthwhile?

When contemplating building a headphone amplifier, many people wonder if it will improve the sound of their system or make it worse, especially if that source is a low-end source like a PC sound card, or a portable CD player or MP3 player. After all, a chain is only as strong as its weakest link, right?

To an extent, the quality of the source is indeed an absolute limit on system quality. But that’s hardly the end of the story. Two other factors make headphone amplifiers worthwhile even when used with poor quality sources:

1. Distortion goes up as the load on an amplifier goes up. If you add a headphone amplifier, this shifts the load from the source to the headphone amp, lowering the source’s distortion. If the headphone amp is of higher quality than the source’s output stage, distortion can be audibly lower.

2. No headphone amp is perfectly transparent: they all change the sound to some extent. A headphone amp’s colorations are an opportunity to change your system’s sound to match your taste. You can even go farther by purposefully designing the amp to change the sound, such as by adding crossfeed or bass boost.

To be fair, there is a risk of worse sound with a headphone amp.

It’s not uncommon to hear reports of higher hiss when adding a headphone amp. If the headphone amp is built properly, it won’t add audible amounts of hiss. If the source is low-end, it’s more likely that it just has a high noise floor, and the amp’s ability to reveal detail is making that hiss audible.

Another problem is that not all distortions in the source will go away when you relieve the load on it. A good headphone amp can reveal these details more clearly than the unamplified source can. This does validate the “weakest link” philosophy to some extent. There is a point where the improvement offered by a better amp is outweighed by the newly revealed flaws in the source.

The best thing to do when you have a source of questionable quality is to try different amps with your source. You can find the breakover point where a better amp gives a worse overall sound with some listening tests.

If you can’t get the amps you want to try easily, start with a CMoy pocket amp. Unless your source is truly horrid, you won’t yet be at the point where the flaws revealed in the source are worse than the improvement you got from adding the amp. If that’s the case and you feel like upgrading, climb the scale of improvements slowly until you reach the point where you need to improve some other part of the system before you can benefit from a better amp.