Amplifying an amplifier

[Case maker]

I recently setup a monitor as a tv (using rca/av to hdmi converter) for my grandfather because his tv break. Also for the audio he is using an headphone with a small amplifier. The problem is that the audio signal from the digital set-top box is really low even with full volume. He says that the volume is too low. So I was wondering how do you amplify the audio signal coming to the amplifier? Even a little would make big difference because he can listen clearly if I use the amp with my phone.

[Psittac]

What are the connections you are using for audio?

 

You could take the output of the current audio, I'm assuming 3.5mm aux headphone jack, and get a 3.5mm to RCA cable and feed that to another headphone amplifier.

 

Best practice is to use a line signal not an amplified signal, but it will still work just don't turn up the original source much, keep it as low as possible and turn up the new amplifier.

[Case maker]

7 hours ago, Psittac said:

Best practice is to use a line signal not an amplified signal, but it will still work just don't turn up the original source much, keep it as low as possible and turn up the new amplifier.

Instead of buying another amp can I use those 3 watt 5v speaker amplifier boards & use it kind of like a preamp? (I was thinking of connecting the L&R speaker output to an audio jack). Is this too much power for the amplifier to handle?