[Master619]

Recently the many of the higher-end DAPs are advertised as having 2.5mm "balanced output" on them, so what is the deal with that? I don't have much knowledge in how audio works but some of my older music equipment like a portable cassette player also have 2.5mm output, and imo they don't seem to be anything special. Why is normal 3.5mm inferior to them? (3.5mm is "not balanced")? I've done some googling around but couldn't find any explanation. Thanks in advance!

 

[Stillhart]

So there are two parts to your question:  2.5mm and balanced.
 
2.5mm:  In the case of DAP's, the main reason they're using 2.5mm for balanced is that you can't accidentally put a 3.5mm (unbalanced aka single-ended aka SE) jack in there.  If you put a SE headphone into a balanced amp, you'll blow the amp.  So 2.5mm is simply there to differentiate it and make it hard to accidentally blow up.
 
Balanced:  There should be plenty of information available on what balanced amplifiers are and why you might want one.  In short, it's simply a different amplifier topology that offers some theoretical benefits to SE.  Whether you hear those benefits in the real world depends on a lot of things from the quality of your headphones to the success of the amp designer.
 
Personally, I think most DAP's have sucky amps and making them balanced doesn't offer any practical (i.e. audible) benefit.  Something like the AK380 in balanced mode doesn't sound as good as using the AK380 into a Cavalli Liquid Spark portable amp (which is SE).  YMMV

 

[Master619]

So there are two parts to your question:  2.5mm and balanced.

2.5mm:  In the case of DAP's, the main reason they're using 2.5mm for balanced is that you can't accidentally put a 3.5mm (unbalanced aka single-ended aka SE) jack in there.  If you put a SE headphone into a balanced amp, you'll blow the amp.  So 2.5mm is simply there to differentiate it and make it hard to accidentally blow up.

Balanced:  There should be plenty of information available on what balanced amplifiers are and why you might want one.  In short, it's simply a different amplifier topology that offers some theoretical benefits to SE.  Whether you hear those benefits in the real world depends on a lot of things from the quality of your headphones to the success of the amp designer.

Personally, I think most DAP's have sucky amps and making them balanced doesn't offer any practical (i.e. audible) benefit.  Something like the AK380 in balanced mode doesn't sound as good as using the AK380 into a Cavalli Liquid Spark portable amp (which is SE).  YMMV

Thanks a lot, very clear and informative. Guess I don't need to worry too much on that for now.