I’m not too sure if frequency response is useful in revealing the sound signature of a headphone in attributes like imaging , soundstage width/height, dynamics, instrument separation, bright/warm, analytical sound, organic sound etc. I prefer to listen by ears than by measurement because if the headphone sounds good to you, measurement is secondary. I really doubt that there is correlation between measurement and sound performance because what measure good may not sound good to you and vice versa. Whether one like the sound signature of a headphone is subjective rather than objective ( like HD800 with very good measurement but some may not like the sound).
It is inevitable that rs1e is compared to ps500e since many listeners may not want to buy both as they are not inexpensive. US$600 to US$700 for a headphone is not decision that one takes lightly. In the past when ps500 is first introduced, rs1i still hold the edge because ps500 is pretty new then. Since then years gone by with Grado having wider distributorships, many heard the sound of ps500 and feel how they are worthy competitor to rs1i in time to come. Naturally listeners will then have higher expectation for the new e series. So listeners may no longer compare rs1e to just rs1i but to its nearest siblings as well. And that is where the issue is. My thought is that Grado has made sr325e and ps500e so good that they surpass the rs1e regardless of sound signature.
So how can rs1e be improved to be in the same standard as ps500e ? My answer is by taking the best ideas from ps500e. Hence my ideal rs1e is a “ps500e with warmer tonality”. Frankly this is what I expect of rs1e after listening to ps500e. When I first heard the ps500e, my first thought is how big the sound has become. It is no longer “soft” as in ps500. It has more slam, full-body weight, more clarity, better instrument separation, more holographic sound and larger soundstage ( quite close to audio technica w5000) that extend beyond the ear cup with absolutely no roll off (no celling, like sky the limit). The sound is really “up close and personal”, and it is mid-centric and vocal-centric , and yet each instrument sound is clearly audible. So if rs1e can take on these ps500e’s personalities but differentiate itself by having a warmer tonality (due to dedicated wood ear cup) giving a free-floating kind of sound without any roll-off ( or lack of energy whatever), that will be sublime sound. Not sure if Grado will create rs1e/rs1x with such sound but I will be waiting