I received the ZS7 as a review sample of the latest offering by Knowledge Zenith. There were no implications that I should present anything but my unbiased impressions. This was an interesting listen for me as I have, in the past, owned a number of inexpensive Asian in-ear monitors but never one from KZ.
As there have been numerous unboxing photos posted in previous reviews of this phone, and also due to the fact that I am not the greatest photographer, I will forgo duplicating the item by item unboxing shots!
All listening impressions and opinions were garnered over the course of a week on and off sessions. All music was lossless, either FLAC or WAV.
Source equipment varied between the following gear, in no particular order.
Samsung Galaxy S5 using UAPP music player.
FiiO M6 DAP
iBasso DX50 DAP
iBasso DX200/Amp5
Pre Box S2 Digital DAC
Periodic Audio Nickel Amp
Overall packaging was appropriate for gear in this price range and comparable to that of other under $50 phones. Items were neatly arranged and presented an overall positive first impression.
Prior to first listen, I did try to find a suitable pair of tips from the included 3 pairs of silicon tips (S-M-L). Unfortunately, none of the 3 sizes yielded a secure fit with the necessary seal. I did resort to using tips from my stash that worked well with other phones of this general design.
Although the ZS7 is shaped and sized much like the CA Andromeda, I found myself having to adjust the positioning of the phones frequently. I am not sure why, as the Andromeda presented no fitment issues. I suspect that the metal housing might have the majority of their weight on the faceplate side as my movements seemed to loosen them depite my best-fitting tips. Although I began my tests using the included cable, I quick swapped it for several of my own cables as I intensely dislike memory wire! While different cables varied in their comfort, I could tell little difference, if any, in the audio performance.
I began my exploration of this inexpensive IEM with some sine sweeps. The overall profile seemed to indicate that the sub-bass and bass would be the star of the show. The mid-range frequencies seemed to be somewhat recessed in comparison to the bass, with a rise in the upper mids, close to where the female vocals would be heard. This was somewhat forward and when listening to several female vocalists did, in fact, tend toward some sibilance. Higher treble frequencies gradually rolled off making the ZS7 exhibit a moderate v-shaped tonal signature.
Moving on to music from my different sources, I found that my Galaxy S5 was more than capable of delivering satisfying levels of music. The enhanced bass of the ZS7 was, in fact, an asset as typically the early Samsung Galaxy phones were not noted for their bass performance.
I didn't notice a great deal of difference tonally as I moved through my various sources although the sound-stage was most expansive when paired with my DX200. No surprise there. Emphasis on bass does tend to narrow the soundstage as bass and sub-bass frequencies are far less directional than the higher audio frequencies. Given the ability to perform very well without additional amplification, the ZS7 makes a fine daily driver when out and about. The added bass emphasis helps overcome outside sounds making it great for commuting on buses or trains. Not so great for commuting via your bicycle!
I played a number of my favorite test files, including male and female vocals, acoustic, classical and electronic compositions. Although I don't listen to much rock, I always include the ubiquitous "Hotel California" by the Eagles.
Somewhat surprisingly, the ZS7 sounded best to me with orchestral and classical selections. The prominent sub-bass and bass lent a sense of weight to the music which I hear during live performances in a hall. Vocals seemed to be rather hit or miss as the emphasis on sub-bass and bass at times distracted from the vocalist. As the heart of most music typically resides in the mid frequencies, I would have preferred the mids to be more balanced. Maybe a touch less bass. Of course much of the apparent overemphasis of the bass can be the result of less than optimum mastering.
My only other Chinese IEM that I currently own and compared to the ZS7 is the CCA C10. Both are 5 driver hybrids, containing one dynamic driver and 4 balanced armature drivers. They are very different, both in build and in performance. The ZS7 is an all metal, very ruggedly built IEM with a prominent sub-bass and bass emphasis whereas the C10 has a lighter weight mostly acrylic build with a well-balanced SQ that serves as a great all-arounder. If one enjoys hard hitting but accurate bass and sub-bass, the ZS7 is the clear winner. If ones musical preferences lean more toward the acoustic or vocal genres, the C10 would likely prove more satisfying.
Overall, I am always amazed at the performance capabilities of the current crop of sub-$50 IEM's when compared to the performance of more expensive mainstream IEM's of only a few years past.