Volume issue DDJ-200

Hi, apologies if this has been asked but I couldn't find anything.

I am using a 'DDJ-200' plugged into my Iphone where I am using 'WeDJ' and have Pioneer DM-400' speakers.

If I just play music via Spotify for example the output is loud as I would expect. When however I play through WeDJ the sound is a lot lower.

Is this normal, I hope there is a solution and something I'm doing wrong.

Any help would be appreciated.

Thanks,

Simon.