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

You should look at NSMT 15SE. They are built and sold out of North Carolina. Fabulous speakers that work with most all amps, certainly yours.

I use them with a Naim NAIT 2...20 watts/channel.

$1995 list factory direct

The good news is LSA makes a few book shelf speakers that could rock your world. The bad news is you have to be willing to suspend disbelief and give them a shot as they are < $1500

I'm rocking the Closer Acoustics OGY with a 10W Tripath TA2024 amp and a REL T5x. 

The OGY are very efficient, very revealing and very well built. The sub provides the extra "oomph" for rock music and movies. The OGY excel at dialogue clarity. They're tiny bookshelf speakers, so don't expect deep bass. 

I am going to look into some of these.  Thanks for the suggestions. I think a small Rel sub would solve most of my problem but it would need to go where my hamper is lol.  It’s a small room with lots of absorption- curtains & carpeting & bed etc. That could be why it appears less loud at full-ish volume.  I just remember when I had a wadia 315 Amp (which is 150 watts) hooked up before and felt it was much louder. The pass labs sounds more heavenly of course.