I have some synths that I've held onto, but don't use much (not because I think less of them, but because of my day job there's just not enough music making hours in a week to deal with it all). Sometimes I consider selling the lesser used stuff, but then I remember I hung onto the ones I have for a reason.
One of those little gems is the Hypersynth Xenophone. Tonight is the first time in maybe a couple of years I've even turned it on, and after re-acquainting myself with some aspects of the UI, I remembered why I don't want to sell it. It has a unique tone, sort of acidy and MS-20 like, yet unique in its own right... the filter is really special, and switchable between 12db,18db and 24db. More importantly it's one of those synths that is just one big sweet spot and seems to sound great no matter what you do with it.
At this point I guess we could call it a rare synth, I don't see any up for sale on Reverb, but they do show up there occasionally.
I remember Kebu saying he liked the tone of these so much he bought two of them. I searched the forums to see if it had ever been discussed before, and it seems Sacred Synthesis was looking into it at one point in time:
https://forum.sequential.com/index.php/topic,385.msg8002.html#msg8002It really is a great sounding mono (that has duophonic mode if you're interested). I don't have anything else that sounds like it.