Just got it all set up, and with the gain setting not a quarter of the way on the Bellari, it's already loud enough and sounding pretty darn good. Too late to crank it, but I'm pleasantly surprised by the volume level. Forgot to mention, the Bellari came with a custom and extremely robust separate power supply to use in place of the original, anemic wall wart. (Included)
I wonder if this has something to do with its performance?
No - almost certainly the wall wart itself would be fine.
Didn't think a non powered passive would do anything.
I have never seen a powered passive.(??)
Most sources output 1V, and most preamp and passives need that cut that back 10-40dB depending on time of day, dirty looks, mood, etc.