My headphone volume is all the way up, but my headphones are still not loud enough
If you find that you have your headphone volume all the way up, but still can't hear very well, odds are very good that you are using a bus-powered (gets its power from your computer) interface, and you have high-impedance headphones. You should never have to turn your headphones up all the way.
Proving your headphones are the problem
Bus-powered interfaces usually have headphone outputs that are compatible with 8-ohm headphones. Many higher quality headphones are also higher impedance (35-100 ohms) and the interfaces don't really have enough power to drive them. You can prove whether this is the case.
- a pair of earbuds like the old iPhone earbuds, with a 3.5mm plug.
- an adapter from 3.5mm to 1/4".
If you plug the earbuds in, and you find you don't have to turn your headphones up as far, you are definitely using higher impedance headphones.
If your headphones are the problem
You have two options:
- Get a different set of headphones. Unfortunately, many of the 8-ohm headphones are inexpensive, and not great quality. You may be able to find something that works fine for you though.
- Get a headphone amplifier. You would connect this to your interface's headphone output using a 1/4" TRS cable (it has the same plug as your headphones on each end). Then plug your headphones into an output on the headphone amplifier. You will need to turn up the headphone volume on your interface, probably to around 3/4, then turn up the headphone volume on the amplifier for the output you are using.
There are some quite inexpensive headphone amplifiers (under $30) that work quite well.