Great for enjoying all types of music!
First off, I really like the shape and size. Most IEMs fit my ears well, but these are small, with a proper shape, that should fit most people’s ears well, even those with smaller ears. The available colors are very nice. I like the red and blue. The logos are fun. The fit and finish is great, and they seem durable. I have no criticisms of the build and design of these IEMs.
The sound is only mildly V-shaped, with the mids a little recessed, but not too much. Vocals, pianos, guitars are all very clear, and not overpowered by the bass or treble. These are warm sounding IEMs, with deep, solid bass, and smooth treble. There is plenty of sub-bass, but also a lot of mid-bass punch. The midrange sounds lush, with the sweet analog sound of a dynamic driver. They are plenty revealing and detailed sounding, but can’t match really good BA based IEMs on very fine detail retrieval. The treble is crisp and clear, and doesn’t sound veiled at all, but is not as airy as IEMs with BA drivers for the treble. The treble sounds a bit rolled off. Overall, I consider these a very relaxing and musical IEM, with a lush analog sound, and enough resolution to hear fine details in recordings. If you want to just enjoy good music for hours, these are great. They are not ideal if you want a neutral and analytical sound. That being said, I like the sound for all genres of music, so they are versatile.
Compared to the TFZ No. 3 IEMs: I like the shape of the S2 Pros a lot more than the semi-circle shape of the No. 3s. They fit much better, and are more stable. The No. 3s just sound bigger. They have more of an exciting, in-your-face sound. The bass is more massive on the No. 3s, and the treble is more pronounced, and a little brighter. The overall sound signature is quite similar on both IEMs though. There seems to be a little more detail retrieval on the No. 3s. I do prefer the No 3s, but not by that much. For the price, the S2 Pros are an incredible deal. If one already owns the S2 Pros, it may not be worth getting the No. 3s also. It would make more sense to get a different sounding IEM, however, I do really like the sound of the TFZ No. 3s, and they are still my favorite single DD IEM. I really can’t wait to receive the JVC HA-FDX1s!
With regards to using one of these budget-friendly IEMs as a stage monitor, I personally would choose the TFZ S2 Pro over the TFZ No. 3, the KZ ZSX, the KZ ZS10 Pro, and the Tin Audio T2. Strictly based on sound, I prefer the No. 3, but the fit is a lot better with the S2 Pros. My second choice would be the KZ ZSX. Depending on your isolation needs, you may want foam ear tips, such as the Dekoni Bulletz. As far as the reliability of these IEMs as a stage monitor, that I don’t know.
Would recommend to a friend.