Itunes Synchronization with any Devices, to less memory

I have a problem with the synchronization of my iphone 5.

I added 10 more songs to one of my playlists. Any yes i checked the memory of theses songs, is under 30mb.
So there are no other changes done by me to itunes. Today i wanted to synchronize my Iphone to get these new songs on it. But know itunes tells me an error message like: "The Iphone XY can not be synchronized, because theres not enought memory for all chosen objects (additional 5GB needed) ".

Same thing with my Ipod Nano. i only use it to hear music in the gym, there is nothing more on it. So i just tried to synchronize the ipod nano to get my 10 new songs on it for my sport. But here happens the same thing :" The Iphone XY can not be synchronized, because theres not enought memory for all chosen objects (additional 2GB needed) ".

And i did nothing to the ipod since the last Backup or synchronization was made. So i think this cant be any wrong action by me?
I tried to google my problem, but doesnt find any kind of solution for this problem. The solutions always tell like, trying to delete some different stuff to get more Space. But seriously? 5Gb more space for the only change of 10 new songs?

Does anybody know, what happend to me right know? Or maybe know a solution, thats not a kind of try to delete something..

I Have 32Gb of Memory on my Iphone 5. And in this moment i have 710mb free space.

I do the same procedure as any time. Just get new music, throw it in your playlist and synchronize. I didnt do any other changes on any setting in itunes or on my Iphone.

I have tried to update my Itunes to the newest Version, but its still the same problem.

I was thinking about to get the newest ios on my phone. Currently its IOS 9.2. But i think they dont fix any kind of this problem in the newst versions. And the problem is still on my ipod nano. Moreover this i did synchronizations with this state of software in the past without any kind of errors. So this couldnt be the point...

Im new in this Forum or community and from germany. So hope you understand my problem.

I would be thankful if anybody has an idea whats going on and knows a solution.

Greets, Micheel