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

Another thought on your speaker quest. I also own a low power Pass

INT 25 amp. I would suggest you adds subs. 

The Pass is great. Keep it. I use the REL T5X sub.

I listen at 65-70dB. You are much higher.

Brands I like: Totem, Sonus faber, Fritz, ATC

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.