Pass X1 pre with black power supply vs full size

Hello,I have an X1 preamp with the smaller black power supply as opposed tho the full sized power supply. Has anyone had a chance to compasre the X1 with the the little black power supply against the larger full size power supply? I have the hybrid version with the black power supply and am wondering, fron a sonic point of view, if it makes sense to upgrade for musical reasons as opposed to just cosmetics.Pass says the larger power supply sounds better and I believe the guys at Pass as they are probably one of the most honest and considerate asdio companies I have ever had the pleasure to deal with. I'm just looking to see if anyone has had the chance to conmpare and what did you notice the diffrences to be?
I had both.The old p.s. was better sounding to me,with a bigger soundstage even though the background wasn't that black as with the new version.After i upgraded to a newer power supply (a 1k option from Pass)i could not recapture the magic i had before and eventually got rid of the unit.
X1 was great with small combos and male vocals but for some reason female vocals were sibilant and spitty.