Preamp output impedance, Amp input impedance and drive ratio? Pass Labs XA25

You've gone a little nuts.  47k input impedance is an excellent value, common in modern solid state amplifiers.  It's high enough that you can pretty much pick any preamp at all without worrying about an impedance mismatch. 

At say 4k, it would be an amplifier that you'd have to carefully match to avoid such issues.  

It doesn't mean anything more than that.  

Conversely, a preamp with very low output impedance can drive almost any amplifier without degrading the sound as the volume changes. 

thank you guys!!

Where you might have an issue is gain. The XA25 is spec’d at 20dB gain, which is on the low side. With your Placette passive, and maybe with some of the others you listed, it’s possible you’ll find things a bit anemic. 

Yeah for now since it's my secondary room I'm trying to use older gear to start as much as I want to buy more gear lol.  

Schiit Yggy DAC is primary source for now going into Placette into XA25 to Acora MBR-1 speakers.  Then see what it sounds like!  Loving my VanityPro HDMI audio extractor to AES XLR into Yggy for TV audio.  M4 mac mini USB into Yggy for Roon.  Phono down the road.  Waiting for more DACs to input I2S input so I can play my SACDs.