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

You may want to attend the SpeakerFest event August 27th in the Phoenix area.

Nearly 20 different makes of standmounts to be auditioned. Two are models

new to the market and making their debuts. Bonus -Raffling off the Elac Reference

Unifi UBR62 speakers. $1,200 MSRP.  Also Special pricing on Bucharts, LSA,

Tekton and Totem. Details on AZAVCLUB.com

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