Qualitative interviews are an ideal starting point to uncover opportunities, in the form of underserved (or overserved) target audience segments and their unmet needs. However, they carry the risk of feeding into your confirmation bias. If you pitch your idea to a friend and ask them whether they like it, they will most likely say yes.
Jobs To Be Done interviews are a better way. They comprise of open-ended questions which help you understand the jobs your target customers are trying to get done, which problems they face, the alternative(s) their using, and how big and recurring the pain is. They also teach you the words your customers use when they describe all of the above, which is extremely valuable in achieving language/market fit.
The big benefit of an interview vs. a survey is that during a free-flowing conversation with your audience or customer, you can dig deeper into what they’re saying. This is not the time for a sales pitch, however, a 15-minute JTBD interview can be the perfect intro to a sales demo, allowing you to learn about your prospect and tailor your demo specifically to their jobs and needs.
Customer interviews aim to understand your current customer base. I recommend focusing on the people who love your product: those who have reached their ‘aha’, ‘eureka’ and possibly even ‘habit’, and who are paying for your product. These are the types of people you want to tailor your marketing, sales and product for.
Besides that, you should run short churn interviews to understand why users are leaving your product.
Audience interviews help you understand members of your target audience who aren’t customers (yet). Audience interviews are great if you simply don’t have any/enough customers yet, are expanding into a new market or target audience segment, or are pivoting your business to serve a new target audience.
I recommend kicking off with 10-15 interviews (to formulate assumptions and gather a first understanding) and follow up with surveys, either with customers (if you have a big enough customer base) or with your audience (external respondents, e.g via userinterviews.com)