Originally Posted by Spadix
What are, concrete, the benefits from using an amplifier compared to listening directly from the source/intergrated amp? I've read many posts that says that, e.g. the Hd600 needs an amp to sound its best- but what will sound better? It would be great to hear your experience.
In my opinion the best understanding comes from thinking about how the two reactive circuits interact, the amp and the headphone. With a highly reactive headphone such as the HD600 (meaning impedance varies over the audio frequency range) the amp can control the headphone driver more or less better depending on the design of the amplifier. You can search on the concept of stuff power supplies for one issue related to the amps ability to control reactive loads. The control of the driver by the amp's circuitry is one of the most important issues related to the move toward having "balanced" equipment for your listening experience.
Without an amp and using only say an iPod's internal circuitry it may be adequate with the earbuds supplied for active (exercise related) listening. But move to a higher end sound using the HD600 and the iPod's circuitry may not even be able to squeak those drivers! An exaggeration I am sure but you may be able to get the picture.