Need suggestions on efficient book shelf speakers for a Pass Labs XA3.5

That's a wonderful amplifier.   Try ZU AUDIO or Klipsch. Tannoy as well.  

https://www.theabsolutesound.com/articles/audiovector-r1-arrete-loudspeaker
 

audiovector R1, tested in TAS with the pass xa60.8, but the 30 should be plenty. 

i've head the pass with dynaudio and it was an excellent match

@puffbojie not ideal especially if the source end is RCAs.
Pick up a pair of balanced Mogami Studio Gold cables from Amazon. Give it a shot and if you’re still not happy, just return them and start checking out other speakers. I have a feeling this will change things for the better though. 

@puffbojie,

Try a pair of JBL 4429 speakers! 😎

Mike