Calibrating with dd1 via Bluetooth question

[Tinkertoy]

I have a 4 channel amp powering (4) 6.5 speakers and a mono sub amp powering a single sub. 
i listen to a mix of fm radio and music from my phone via Bluetooth. My head unit has no CD player. I can use the dd1 tracks either from a usb stick or via Bluetooth. Which is the preferred method? If using it via Bluetooth what volume should my phone be on? I assume then when listening to music the phone should be at that same volume? Thanks 

[Dafaseles]

Since you mostly listen to things via bluetooth, I'd set the amps via bluetooth. I don't know how you would go about finding the max volume of your phone without distortion, so if it where me, I would just have it 3 or 4 clicks from max volume and when listening to it in the car never turn it up past that

[Tinkertoy]

Thanks! It’s actually in my boat. I may try doing a test with the head unit all the way down and see where the phone distorts too. I’ll just play around with it and see what results I get 

[Dafaseles]

Just now, Tinkertoy said:

Thanks! It’s actually in my boat. I may try doing a test with the head unit all the way down and see where the phone distorts too. I’ll just play around with it and see what results I get 

If you figure out a way to find the max volume without distortion on your phone, let me know please. I have an I pod that I use for music in my truck and that's what I'm going to use to set my gains using the bluetooth (also using the DD1). It would be nice to know the max volume of that thing while tuning.