Are NHT speakers know for being inefficient?

I know this isn't high end audio but it is what I have now. I actually am using my NHT 1.1 speakers that use to be my rear speakers as my mains. I was using some Carver AL-III with a Phase Linear 400 as mains but that is not the case now. I have since bought and older Pioneer Elite VSX-07TX. Not a bad deal for 162.00. My question is that now I have the NHTs up front. I really have to turn up the volume alot to get them going. The receiver is rated at 110 into two channel and 100 into 5 channels. The speakers are rated at 150 max. I can turn it all the way up and it sounds great, no clipping or any rough stuff. But still not THAT loud. I just can't imagine that these speakers are that inefficient. I am using a Sony don't remember the number dvd/cd/sacd player. It is around 300.00 new. It seems to me I have read somewhere that these older NHTs circa 1993 where on the inefficient side but this is a little suprising. I do notice if I turn them from stereo mode to Dolby Digital or THX they are louder but still not that loud. For normal listening level in stereo mode I am having to turn it up half way. Anybody got anything to say on the subject. I also have done all the adjustments with the receiver, although the vsx-07tx doesn't allow to much user tweeking. I am using optical and analog cables and it makes no difference whether I am listening to vcr, tv, fm. Well actually the optical is a little better but still the same basic thing.
NHT was known for acoustic suspension speakers, which are less efficient than ported or bass reflex speakers. That could at least partly account for what you are experiencing.
Yes, the NHTs (and many, many other) 2 ways are insensitive if you consider 86dB SPL insensitive. Do not confuse sensitivity with efficiency. The speakers are reasonably efficient.

I doubt the problem is with your speakers or the load they present to the amplifier. I have 86dB SPL NHT 1.5 that can be driven to deafening levels with a 40W tube amp. I think you should take a closer look at the Pioneer. Swap out your poineer for the Carver/Phase Linear combo and see what happens. Try your previous mains speakers with the poineer and see what happens. Obviously, something has changed in your system, so try to isolate the problem by swapping components one at a time.

NHTs, especially the larger ones, may present a challenging load for an amplifier, but in my experience, are not particularly "inefficient" or rather - insensitive.

Good luck,
Well, I have sold the other components. I am moving to Tuscany for a year, needed the money. I do have and old pair of Polk bookshelf speakers that are my rear speakers. That was my next thing to do was swap out tonight. If that doesn't seem to answer any questions I guess a $20.00 diagnostic fee is in line. I have order an owner's manual but it is not here yet. There just doesn't seem to be that much to tinker with as far as settings. I will let you know what comes of it.