why is the audio low when listening to Itunes radio

Thanks Bob. I did submit feedback to Apple, fwiw:

http://www.apple.com/feedback/itunesapp.html

Enabling Sound Check on other Apple devices doesn't solve the problem of overall system sound volume ending up being turned up too high to compensate for the low output volume in iTunes Radio.

You could write Apple and ask them to stop using the Sound Check normalization on iTunes Radio, or at least use a more reasonable compromise volume setting, like -12 LUFS or -10 LUFS. That's what Spotify did after complaints of low level with their setting "make tracks same level" checked. They upped the normalize to about -12.5 LUFS, so Spotify with the normalize setting is a few db louder than iTunes Radio playing the same songs.

I would start by contacting iTunes support:

https://getsupport.apple.com/Issues.action

The whole thing is really dumb, because you can preview album tracks in the iTunes store at original full CD volume, with loud commercial Pop songs sometimes reading about -7 or -8 LUFS, but then the same song playing on iTunes Radio will be at -16 LUFS, about 8 or 9 db lower in volume, which is a lot. -16 LUFS is much too conservative IMO.

I also just found this, which has useful links as to why this is happening:

https://discussions.apple.com/thread/5498520?tstart=0

Same problem here, and I've seen others reporting this as well. Anyone have an explanation or solution?

I have noticed this from day one on my iphone, ipad, Apple TV, and rMBP. All my friends and family that have Apple products notice the same thing. I have an active Match subscription and others don't so I have no idea why the haven't fixed/acknowledged this issue. I'm not trying to blast the volume to 11, but when I listen to iTunes Radio I have to raise the volume and like others if I switch to something else the sound is full volume. Also, when listening to iTunes Radio and I get an alert(text, email, notification, etc) that volume is much louder than the radio -same volume as if not listening to iTunes Radio. Well guess I can always use another service. Come on Apple, you know Steve Jobs would not have allowed this!

I found out why this is. It's because Apple applies the equivalent of Sound Check to iTunes Radio. It normalizes (equal volume) all the tracks to -16 LUFS. In general this makes most commercial releases lower in volume than elsewhere because most start off at about -10 LUFS. Apple doesn't consider this lower volume an issue. To them Sound Check is a fix for overly loud commercial releases. I wish someone from Apple had answered this question a long time ago. I had to find the answer elsewhere.

Thanks for the info Bob. I'm not sure how you found this out or where it's documented, but now that we know the cause, is there anything we can do as users to counter the normalization that Apple is applying?

Or you could turn on Sound Check in iTunes preferences on all of your Apple devices. Then all of your iTunes libraries 'should' match the same low level volume of iTunes Radio. I guess that's what Apple would say to do.

Thank you to bhrabin for the link to provide feedback to Apple.

My issues with iTunes radio: Volume is so low, that I must turn up the volume on the car radio to it's maximum to enjoy the music.

When playing purchased itunes songs, you do not have to MAX out the car's volume to listen/enjoy the songs. An Itunes Radio version song is at least 50% of the volume that a iTunes purchased song is.

iTunes radio seems to be trying to save us from ourselves? Information I found about the issues I'm having.

http://www.digitalmusicnews.com/permalink/2013/10/28/itunesloudness

Another problem I have is with an iPhone 5S using the headphone output port not playing songs loud enough for my tastes(Apple earbuds or Car Aux port). An older iPod with the same music plays wonderfully. Never needing to MAX the volume out on it. The quality is much better not having to MAX out the volume too!

I wish Apple could explain the changes their doing to iDevices, iTunes Radio and other issues with volume limits they now have to impose on the USA.

Everything on iTunes Radio is about 6 or 7db lower in volume than the same tracks in the iTunes store. If Apple has a reason for this, I haven't found it.