Not meaning to be argumentative, so take this as genuine curiosity:I define timbre AKA timbral accuracy as "what lets us tell apart a musical instrument or voice, even when they are hitting the same note at the same fundamental pitch and loudness". I've been playing in a band for the last 20 years and think the Senn IE600's DD sounds more natural in timbral accuracy when it comes to acoustic instruments like strings, woodwinds and brasses. The Euclid, like most planars, have very fast transients and rapid decay, so the note weight and timbre of instruments sound a bit off to me (but they have superb technical chops cause of the planar physics!). Euclid trumps most other similarly priced competitors in technicalities and that's something I appreciate.
I thought that timbre is basically created by the physical characteristics of the instrument - The way the string vibrates, the wind over a reed, etc.
Recording and playback doesn't recreate that, instead, it measures transient moments in time, then plays back those transient moments as accurate as it can.
Given that, wouldn't the euclid with it's high transients and rapid decay be able to recreate those original recordings more accurately without introducing 'interference', and thus have better/more accurate timbre?
I'm not expert, so I'm asking out of curiosity, as you know more than I.
I tried a slightly larger tip: You won't be surprised to hear that the bass improved, and now it's much more dominant, and louder than the euclid. In general, I still prefer the way the euclid renders bass, but I now agree with you, the ie600 is in no ways light on bass, without being overwhelming.Perhaps you can try with various other tips (silicone or foam), or even tips of various sizes, to see if you can get a better seal?
I'm liking the ie600 quite a bit more than I did before; though the comfort is slightly diminished.