I ended up spending most of the day (minus Formula racing practice for this weekend’s race) listening to both the RS1x and RS1e. I used a HeadAmp Gilmore Lite mk2 with the optional Discreet Regulated Power Supply. I find their combo a good match for most of my phones and my Grados definitely like it.
I took turns listening to each with the same musical selections spending 15 - 30 minutes for each & then doing the same for the other. BTW, both phones have significant play time on them (200 hrs each) so break in was not an issue.
I found the vocals on the x were placed slightly back compared to the generally more forward e. The x was more neutral and natural sounding. On massed vocals the e started to sound a little bit splashy while the x proved to be more articulate with them, better placing them in the mix. String plucks & guitar
sounded great, a common Grado trait but very impressive here. I found the sound stage on the x to be more open and slightly wider.
The x has a more impactful and detailed bass, not boomy at all. The e was not with as much bass which did not integrate as well in the whole as the x. Cymbals sounded more true to life on the x.
I always found the RS1e to be an enjoyable listen and still consider it a good headphone but to my ears the RS1x out performs it across the board and establishes itself as must listen to anyone considering headphones in the $1000 price range. It is also a very good value.
My best advice would be to try to get a listen in or perhaps a loaner. New out the box they will sound good but definitely evolve after 50 to 100 hours and will sound better especially past 100 hours.
Of course these are my impressions and may not be the same as yours so hopefully you can get a chance to hear a fully broken in RS1x.
In the meantime I highly recommend them.
PS. I also have a pair of original vintage RS1 phones that I cherish but they are currently on loan to a friend.
Have fun……