Nice read for me between the HP-1/PS1K, thanks for your comparison between them.
Although I've never heard the HP-1 (and probably never will) from your description of it's sound signature, It sounds like my impressions of the Alessandro MS2i (which I owned) and would describe their sound signature very much, if not the same exact way you describe the HP-1. As you know, I've been trying different HP's recently comparing them to my PS's…I guess I'm trying to find something that may suite my tastes better, why, I don't know…because every time I try a different HP, the PS's suite me much better. I'm listening to them as I write this, and have been for the past 3hrs, and I feel I'm wasting my time, like a dog chasing his tail looking for something that better to suite my tastes, but I think tonight I'm finally realizing this may be the end game HP for me. I have one more HP (well maybe 2) that I would like to compare to the PS's, which are the LCD-2 and the X. I waiting for delivery of the LCD-2 Rev.2 right now, so I'll hear/compare how they are for me. As for my RS1i/WA6…they are my other flavor combo, which I have, and never will have any desire to compare with anything!
Glad too hear your enjoying both, you new PS1K's and the HP-1's, enjoy!