Yep headphones work. Stereo is a newer pioneer system. When I plug the phone in the music stops playing from the phones speakers, but nothing comes out of the stereo speakers.
as for your stero, listen to a CD or Radio or something at what you consider a "normal" listening level. switch over to your berry without adjusting the volume on your stereo. adjust the volume on your berry so its "close".
I'd be a little concerned with blowing your pre-amp on your pioneer, but only if you have both the berry and the stereo CRANKED. if its at lower volumes it should be just fine.
You can't hurt the BB by cranking the volume to max if you aren't using the BB speaker. I have to turn up the BB all the way, and my vehicle stereo nearly all the way up to make it even at a comfortable listening level. Unfortunately there could possibly be slight clipping. The only thing to be careful of is that you turn the BB down before you unplug your AUX cable or you'll send full volume to the BB speaker. Likewise for the device you are playing through. You don't want you car or home stereo at a high volume and switch over to radio or other. Results could be bad.
Crank away on the BB, just make sure to turn it down before disconnecting.
You can't hurt the BB by cranking the volume to max if you aren't using the BB speaker. I have to turn up the BB all the way, and my vehicle stereo nearly all the way up to make it even at a comfortable listening level. Unfortunately there could possibly be slight clipping. The only thing to be careful of is that you turn the BB down before you unplug your AUX cable or you'll send full volume to the BB speaker. Likewise for the device you are playing through. You don't want you car or home stereo at a high volume and switch over to radio or other. Results could be bad.
Crank away on the BB, just make sure to turn it down before disconnecting.