[TidalWave]

I have some very newbie questions regarding using an external amp connected to a cell phone via 3.5mm port:

- if my headphones have a cable with built-in microphone and in-line controls, will those functions still work with a mobile amp between the headphones and the phone?

- what if I use an amp/DAC via microUSB port instead? (Like Cayin C5 or Dragonfly)

- what volume should I set my phone to vs. amp volume?

 

[ProtegeManiac]

- if my headphones have a cable with built-in microphone and in-line controls, will those functions still work with a mobile amp between the headphones and the phone?

No. There's no connection on the + contact for the mic from the 3.5mm cable to the amp.

- what if I use an amp/DAC via microUSB port instead? (Like Cayin C5 or Dragonfly)

A few handle mic signals but not those. Check the SoundBlaster G5 and E5 for that. They have the mic input circuit primarily for their target market can tell strangers online what their mothers were doing last night, but AFAIK it can also be used to say hello and stuff.

- what volume should I set my phone to vs. amp volume?

If using USB, Android now disables even digital volume control when detecting digital output, same as Win10.

Using 3.5mm headphone out, that's tricky. You have to figure out what output voltage is optimal so yu don't rely too much on amp gain which means the amp's distortion and noise levels will be high, but not too high output voltage settings that the phone's audio chip's amp section is struggling and it is distorting or has noise.

 

[bixby]

Protoge has good advice, I would add in all the years I carried amps with phones and idevices, somewhere around 75-90% of source volume worked well, wmmv

 

[buke9]

The C5 is just a amp and the Dragonfly is a amp/dac so the C5 would need to be adjusted for volume but the Dragonfly would not.