The Sennheiser IE400 Pro is, indeed, a satisfactory pair of IEMs that serve different purposes. No matter what your need, IE400 Pro will have a solution for you. Excellent fitting along with its neutral and lively sound signature won my heart over from other models. The accuracy and maturity in tuning single dynamic driver has once again portrayed the success and expertise of Sennheiser in this industry. With the launch of IE PRO series, the legacy of Sennheiser continues and they have proven to the world that they are still relevant even after more than half a decade. The review of IE400 Pro had been posted on Headphonesty: https://www.headphonesty.com/2020/05/review-sennheiser-ie400-pro/
Modern and minimalistic, the excellent low-profile design of the IE 400 PRO contributes to the exceptional comfort which has allowed me to enjoy the IEMs for hours and hours. Despite its succinct mid-range, the IE 400 PRO provides excellent value simply because it is a well-designed product, with a sound quality that few at the same price point could match. https://www.porta-fi.com/sennheiser-ie-400-pro-and-ie-500-pro-review
One of the best IEM I ever tried. The fit is great and the sound is awesome. Would definitely recommend this to my friends and colleagues.