What is inadequate about pre-amps?

[AmanGeorge]

When people say that pre-amps aren't as good as dedicated headphone amplifiers because the headphone out is implemented as an afterthought, what exactly does that mean? The plug is sub-par? What are the technical deficiencies of most pre-amps as headphone amplifiers?

 

[pyramid6]

Pre-amps are usually used to bring a source up to a certain dB level. A record player produces a low "volume" signal and a preamp brings it up to a level that the amp can use. Notice the "Pre" part.

You thinking of an integrated amp. It depends on how they are built, and how they handle the power that flows through the headphone. Most things built as an afterthought are not going to be as good as a dedicated one. At least on hopes.

EDIT: or maybe you were talking about preamps as headphone amplifiers.

 

[grawk]

There's not a lot of difference between preamps and headphone amps. The big deficiencies would be in gain. The main question becomes one of voicing. I owned an NAD 116 preamp for a while that was a decent headphone amp. Ray Samuel got into headphone amps after Jude liked his preamp as a headphone amp, I believe. Etc.

 

[sacd lover]

Preamps are usually driving loads above 10K ohm .... most amps have input impedances from 50-100K ohm. So many (not all) preamps have output impedances of several hundred ohms. Moreover, preamps are more suited to voltage gain than current gain. Look at your typical 12AX7 tube preamp .... that tube has virtually no current output and a high output impedance.