NAD M33

crank that VC until you get the action you need and disregard the numbers shown.  I used it in all its configurations. bi-amping it internally didn't yield much more than the single amp config. It gets most speakers moving pretty well but if you stretch its legs, it ends up showing you the limits of its power.  I will say it's an impressive bit of gear for most though.  IMO it has a bit too many options for the average user to "get wrong" in the setup leaving the user to misinterpret the misconfiguration as something being wrong with the unit.  I found using it as a digital source unity gain/pre-out into my Audio Palette for the final VC... tolerable...which is basically a thumbs up;)

Just to echo what other owners/former owners have said.  Yes, regardless of efficiency of the 3 different speakers I paired it with (none super efficient but roughly 92-85 dB) it needed to be at least 1/3 the way up to be audible and generally around 45-50% for normal listening.  (FWIW, I hated the built-in streamer and disliked the DAC.)

I had the M12 preamp and M22 amp combo a while back. I enjoyed the M22 for what it is, nice amp, but it’s not going to compete with my big VAC tube amps. By contrast I didn’t think the M12 was very good at all, though I loved its interface and features. So perhaps the M33 is held back by its preamp stage? 

The amp stage alone should be quite good, though with M22 I found it really benefits from a sweet tube pre and maybe a bit of a "dark" source too (e.g. VPI tables). Otherwise it can come off as too "dry" sounding - and the matching preamp just made that aspect worse. 

Try to borrow a tube pre and pipe it in if you can. If you don’t like the M33’s low preamp gain, that would help there too (it’s a low gain you’re noting, not low power - plenty on tap there). Ironically in the more distant past I had a NAD M51 preamp/DAC, and my memory of that one is MUCH better than of the M12. 

The BlueOS setup & usage was way way worse several years ago, but it still finds ways to annoy me when I run it again, once in a blue moon. I despise getting bugged for updates, when I just want to listen. I am a software engineer, and just no - this does not belong here, in my music! Also back then, you couldn’t just plug in a SSD drive of music, either. I almost chucked the Node 2i out the window a few times. 

I recently purchased the M33 v2 this year, and it does the same thing. The phono input has the lowest signal "strength" if I may call it that, of all the inputs.  The streaming section is the strongest. CD and tape are somewhere in between depending on your equipment. I'm running a teac vrds 701 cd player with the volume of the output at 85 and it's still a touch lower strength than the streamer.

-60 db for me is very quiet listening level (ie I typically start my morning on the streamer with a cup of coffee at this level)  and I have very good hearing - Hope this helps.