Is louder better?

Yes, the morning hours is when electric is cleanest, and the quiet is deafeningly awesome for audio listening. 
   Love listening critically from about 12-4 am. 

Yup! late night low level is just the best!

I think louder is better (depending on circumstances). If I'm cleaning my house, I don't need to hear J.S. Bach at tremendous levels.
If I'm wasted (a quarterly event) listening to LZ or Jimi, and feel like cranking it, I don't want the system to wimp out or fall apart.
This is how to tell if you got your money's worth.
All systems, MOL, sound good at moderate levels. You pay the big-bucks for something that sounds the same at whatever level you choose.
This is, to a large extent, dependent on room size. Blasting music in a small room can't help but trigger all kinds of foul resonances and reflections. My dream room is 30 X 50 X 12. Peace

Syntax, mastering92 is on the right track. Every recording has a volume it sounds "right" at. This depends on how it was mastered and the genre of music. 

Your ears change frequency response with volume. At lower volumes bass and treble disappear at high volume they can be overwhelming. 
Google Fletcher-Munson Curves. Loudness compensation is  way to beat this. It raises the treble and bass at low volume. 

I'll listen to rock at 95 dB once my ears have warmed up. If you try to listen to a string quartet at 95 dB it will cut your throat. I'll listen to that at 70 dB. I'm talking about peak volume. Many systems will not play at 95 dB effortlessly. They are clipping the peaks. IMHO there is never such a thing as too much headroom. Depending on your speaker's efficiency you need to make sure your amp can handle peaks of 10 times the power or about 10 dB over your loudest listening level in my case that would be105 dB.  My speakers have an efficiency rating of 89 dB/watt/meter. Every 3 dB requires twice the power. 92 dB = 2 watts. 95 dB = 4 watts. 98 dB = 8 watts. 105 dB = 38 watts. My amps stay pure class A up to 25 watts so, they are staying class A except for the very loudest peaks at my loudest listening level. There are speakers that have an efficiency rating of 110 dB/watt/meter just fine for those SET amps and speakers that have an efficiency rating of 82 dB/watt/meter requiring 132 watts. Rock concert level would require 250 watts. This is pretty basic. The various classes seem to handle power differently. I can usually identify a class A amp. They have an effortless character missing in the other classes. They also tend to sound more powerful than they actually are. The Krell KMA 100's I had sounded more powerful than every one else's 200 watt amps. Was it the class or the size of the power supply or something else I do not know and my experience is anecdotal. But for what ever it is worth I will never use anything but class A for my main amps. 

It all depends what music you are playing. I doubt that the Mantovani crowd would appreciate high level listening!