I have not heard the BHK pre, but I’ve owned an XP-10, XP-20, and finally a gently used XP-30. I’ve also owned Audio Research and Conrad-Johnson tubed designs.
There is a certain “je ne sais qua” to well executed tube designs. No doubt. That said, Pass (and some other contemporary) designs have gotten “close enough” for my tastes.
The good thing about the BHK is the ability to “roll tubes” to tailor the sound to your liking. The bad thing about the BHK is the ability to “roll tubes” and keep second-guessing yourself.
My $0.02: get a used or refurbished XP-20 from Mark at Reno HiFI and a BHK from PS Audio and do your own shoot-out. Both Reno and PSA support no-cost home trials, although with Reno HiFi you’ll pay for shipping one way.
Oh, yes. Using the XP-30 in conjunction with the DSD Sr. It’s a nice combination.