The PS1000 is a really bright headphone out of almost any amp (bright with the upper treble only, not with upper mids like the RS1). You would need to either use aggressive EQ or get an amp that’s kind of sloppy and syrupy to reduce the brightness.
I suggest you try some EQ first to see how much you need to adjust the treble to make it not bright for you. If it’s more than, say, 2 or 3 dB of EQ, then your ears/brain may not be the best match for the PS1000.
I know, I know, this is the “fan club” but the PS1000 is a divisive headphone that does not mesh with everyone because of its frequency response. So that’s why I suggest trying some EQ before spending money on an amp that might need to seriously warp the FR to make the PS1000 sound the way you want.
On a less expensive note, a Little Dot 1+ with some Voshkod tubes might do the trick for cheap... Cheap I know, BUT it worked well when I auditioned the PS1000 and I run it daily now with a number of low impedance cans.