:) +1 Rudi, hiss is something impossible on ES iems and ciems.
I did some AB next night, here are some of my observations about the differences between ToGo!334 and S-EM6. I try to distinct objective qualities from subjective perceptions, also the sound signature.
EarSonics S-EM6 compared with Fit Ear ToGo! 334
Methodology : used on Hibino HDP-R10 (and iBasso DX50 for confirmation) with tracks in flac level 5 and mp3 320ko/sec. Volume listening was set up in order to have the same perception of volume in terms of decibel. 206 for S-EM6, 197 for ToGo! 334, that is more sensitive. The ToGo! 334 is also more sensitive to breath than S-EM6 (observed on iBasso DX50 for example).
Both of them where used with original eartips. The fit is to my ears easy to find with both, but ToGo! 334 are more out of the ears, S-EM6 in ears. The fit is very important for both of them, without it you don't have the bass response and the highs resolution. Both are confortable, more than lower cost IEMs.
Soundstage : both have an impressive soundstage, S-EM6 is more deep, ToGo! 334 is more wide. Vocals is more recessed, laid back, on 334, which give a soudstage seen from above, instead of an on-stage soundstage of S-EM6. S-EM6 gives the feeling of a non-limited soundstage more than the 334, although it gives too this feeling, but less. S-EM6 push forward the stage when 334 lateralised it more, giving a soundstage more wide than on S-EM6.
Transparency/clarity : The 334 seems to be more transparent on certain low frequencies than the S-EM6, which seems to give more transparency on certain high frequencies. Vocals are more transparent on S-EM6 with his front approach than on 334.
Balancing : S-EM6 is clearly more balanced than 334, which has bass and highs emphasis in comparaison. 334 is more hifi instead of S-EM6 is more neutral monitor.
Resolution/details : S-EM6 has more resolution on low frequencies, bass and sub-bass have a high level of resolution that doesn't have 334 because of his presentation. Highs have just different philosophy but same level of resolution. Nevertheless 334 are less realistic on cymbals, which is linked with the question of coherence of the placing.
Coherence and presentation : Two things very different. 334 sound analytical when S-EM6 sound global approach with interliked instruments. Instruments sound more alone on 334 than on S-EM6 which offers a very coherent presentation. Presentation of 334 give more place for bass, S-EM6 gives place for air between the instrument. The S-EM6's layering is more precise but it is easier to be focused just on one instrument with the 334, when it is easier to be focused on the melody with S-EM6. Two philosophies very different that match with the balance of each.
Harmonics perception : harmonics are on both audible, sign of high end IEMs, but the harmonics are in an easiest way perceptible on S-EM6 with his global presentation.
Speed perception : at the first listening 334 seems to be more speed than S-EM6, especially on low frequencies. At the end perception of speed is global on S-EM6, which goes with his coherence, when speed perception on 334 is more on each instrument, which can gives a lot of excitement on bass rythmic, vocals rythmic, etc. when S-EM6 purposes a global rythmic approach.
Lows : 334 has low frequencies emphasized when S-EM6 is more neutral. That does not mean S-EM6 is flat, that means S-EM6 uses bass response when it is necessary when 334 has louder lows at the bottom. Lows on 334 are more fun and exciting, when on S-EM6 they are more controled and precised in termes of placing. Level of details is almost the same, in depends from tracks, but both have high level of details.
Mids : In comparaison 334's mids are recessed and S-EM6's are forward. Both are very nuanced, but sometimes S-EM6's are more tactile.
Highs : S-EM6 is more liquid than recessed. Very smooth treatment on this frequencies. 334 are more emphasis, almost aggressive in comparaison of S-EM6. Level of details is the same, sometimes more on 334, sometimes more on S-EM6.
Bass texture: both are organic but in a different way. 334 is dark typed in comparaison of clarity of S-EM6. Both has a good extension in bass response, but S-EM6 goes further, deeper.
Vocals : the forward presentation of S-EM6 on vocals brings transparency with smoothness; S-EM6 is a non-fatiding and non-sibilant IEM. 334 has a laid-back presentation of vocals, without characterized him as a laid-back IEM, it is very well nuanced and controled. However in high-mids 334 can be more fatiding than S-EM6.
Highs clarity : S-EM6 are more realistic on many instruments as cymbals or violon although 334 are more emphasized on these frequencies. Extension is almost the same, highs are not recessed in terms of presentation on S-EM6, but not as loud and bright as with the 334.
Both of these high-end IEMs offer a lot of pleasure to be listened, not one more than the other, it depends on tastes and on technical aspect that tempt you. To my mind 334 has a more hifi approach when S-EM6 has a more technical approach that look for the right sound.
Both gives almost everytime the same level of details revealed, a very good presentation, depending on what is more realistic to your ears (lateralised or not, deeper or wider, pushed forward on-stage or laid-back placed).