Ipod line-out vs headphone jack

[QwertyAccess]

Does anyone know if line-out on the ipod when rockboxed is equivalent to the volume being 0db? I heard that apple's lline-out on the oringinal firmware was supposed to be the equivalent of 70% volume of the ipod.

I plan to hook up a headphone amp through the headphone jack, and an external battery power through the dock connection. So i'm wondering what would be a good volume to set the ipod at. It is usually recommended to set volume to 60-70% of full volume if using headphone jack.

[Llorean]

0dB is a "line out" level.

[QwertyAccess]

i was thinking that, but since 0db seemed to be ungodly louder than ipod's original 100% volume, it seemed odd... There shouldn't be any risks running it at 0db although the amplifier will be on i imagine?

http://store.apple.com/1-800-MY-APPLE/WebObjects/AppleStore.woa/wa/RSLID?mco=40A4EF0E&nplm=TL193LL/A
Thanks, haha and i hope this external battery works without a hitch, I imagine when its plugged in the ipod battery % just stays at 100% till the pack is dead.

Anyone here got any external battery suggestions?

[saratoga]

Ipods sold in Europe have lower volume through the headphone jack (in Apple's firmware) because of some EU law.  Normal ipods and those running Rockbox should be the same though.  IIRC theres actually just one output on most of the Wolfson DACs, and its just split into low and high impedance lines for headphone and line out respectively.