Now you have identified more specific who is going to work with the products, targeted interviews can be conducted.
Who comes into contact with the product on a daily basis?
Qualities interviews usually give you more insights
The “Think aloud method” can also be a way of interviewing.
Have the user go to work with an existing product and at the same time say it aloud provides you a lot of information then that you would have when the interviewee just have to explains his thoughts about a certain product.
Tip: if prototypes are already available, it is better to have the respondents compare different components with each other than just asking what good or bad a certain prototype is.
By comparing, more specific information emerges and there are already gradations of appreciation that can yield subtle disentanglement fits.