Preamp recommedations for Pass Labs XA-100.5

I took my Pass XA160.5 over to a friend's house to compare the Pass XP-30 to the Ayre KX-R(?). They both sounded excellent, but if I were to buy one, I would choose the Pass pre. It was slightly smoother with less emphasis on the high frequencies. They seemed equally detailed, but the Ayre seemed slightly tipped up. I would describe the Pass as neutral or slightly warm, where the Ayre was definitely on the cooler side. The Pass seemed just slightly better balanced to me, though I'm sure others would hear it the other way around.

I own the XP-20 which is also excellent, just not quite as refined, smooth and detailed as the XP-30.

I've had the Pass Aleph P, X1, and XP-10.
I now have the XP-20. I'll admit it. I like Pass preamps.
There's an XP-20 on Audiogon right now. If you buy it for $5500.00, you can listen & flip it for what you paid, if you're not happy.

Agree with Erndog. Best preamp is no preamp. I drive my XA30.5 direct using 64-bit internal volume of Jriver MC17. Even my Passion Audio Synthesis passive was colored in comparison. If all digital sources, I'd at least try direct before spending the money.

Erndog, thanks for letting me know that I was in the wrong Thread, my question to you is I have a
Sim Audio Moon power Amp and I would like to know if the Audio Research SL 27 Pre- Amp would be a good
match for, it thanks in advance Erndog. Tango.