And someone loves to say opposite of the opposite of a specific statement Add a wide bore to ES4 and compare it with stock ZSA(as ZSA being the expensive one). I can agree that ES4 are uncomfortable but are better than ZSA when you have wide bore plus if you neutralise it with Neutraliser, ohh my god it stages fantastic. Guitar plucks gets surreal and piano reverberation can be heard which were missing in equalised ZSA. I agree with the breathe in ZSA is prominent and I quite like it but ES4 equalised with wide bore is also not behind. Comparison: Charlie Puth's How long FLAC 24bit 192kHz Both IEM equalised for my ear Bass ES4: it does everything effortlessly, subbass extension is amazing for price and separation, which is hard in bass is also very good. Its decay is natural yet faster than counterparts and has enough slam and body to it. I can hear bass instruments separately. ZSA: faster than ES4, and less impact and body. This quick transition of dynamic driver is noticeable. It makes me remember the TinAudio T2, just slight more mid bass on ZSA. It just separates the bass instrument completely. Bass guitar and rumble don't blend and are played separately. Mids ES4: lovely, if given space. I mean to say, if mid centric song is played, it just does what I needed an IEM to do. ZS10 was placed to backward and was hollow and recessed compared ES4. It sounds like Kinera Idun(standard) without that detailing. I mean to say, that the mids are uplifted compared to ZST and ES3. Mids coherency is also spot on. Charlie Puth vocal are separated from everything and is portrayed very clean. Instrument doesn't clogs vocals like other KZ. ZSA: recessed compared to ES4, stage is smaller but image of tone is better. Piano and violin sounds lifeless compared to ES4. The depth and reverb of ES4 is missing and air on them is increased making some strings sharper and sibilant. The best part is the background voices comes forward in ES4 which, initially was very weird but then I enjoyed it after sometime. It was more prominent than my 64audio u18t, but still on enjoyable level. Breathe was also more than u18t, but overall vocal information and instrument was recessed. Treble ES4: something like ZST, but 8kHz dramatically reduced. This made the instrument less sibilant but increased the sense on lower treble making it sibilant, but after EQ, it gets phenomenal. Sometimes making me think, is this seriously a 10$ stuff(I bought it for 10$, actually 15$). The problem is with cymbals, as they are now lowered, I was able to listen the details now as they are not masked with energy like ZST was. The cymbal sounds to linger a bit which can be sometimes annoying. Breathe harmonics can get fundamentally more detailed due go this, but fundamentally its not like ZSA, which makes it a little more enjoyable for me. ZSA: lovely treble tightness but harsh to me as my resonant peak is 6kHz. After EQ, I noticed the treble to be more tight and air representation to be more tight and extended. It gave the stage some space and blackness overall which I liked but they were still close compared to ES4. ZSA loves to show you thread of a clothes whereas ES4 let's you appreciate the clothes altogether. ES4 stitches instrument yet let you hear details and ZSA separates them. But why do I like eq ES4 over eq ZSA is because it does piano, violin or I would say instruments better. My bösendorfer concert grande 290 imperial recording sounds more accurate on ES4 compared to ZSA. ZSA makes it sound like Steinway reverb with bösendorfer string(lack of the gravitas, weight and the individual reverb characteristic) making Eq ZSA sound coloured compared to Eq ES4. I will agree with air and overall clarity, separation being better on ZSA. But ES4 is a jack of all trade and tries to do everything a little right in KZ house compared to ZSA.