External Sound

Hi

I've recently purchased a pair of the Pro 2 earbuds. They are really good, but seem to have one major drawback - I work at home with my partner, and she can hear what I'm listening to almost as clearly as I can. I replaced a cheap set of Amazon-no-brand earbuds with these - with the cheapy amazon earbuds she could barely hear it. With the Pro 2, she can hear it over her own earbuds. 

Is this a known issue, or is there some settings can be tweaked to do with the ANC that might be causing it?

Thanks