Does It have to be loud?

No, it doesn't have to be loud. I listen typically anywhere between 60 and 75 dBs, and it is plenty loud for me. Could I play it louder and as clean (i.e., without distortion) on my system? Sure, but I see little point to it. The fact is that the human ear is a very sensitive organ, and extended exposure to high dBs is likely to result in major damage. As a musician, I have always used hearing protection when gigging and rehearsing ... and, I'll tell you this ... my bandmates who failed to use hearing protection now are hard of hearing. OTOH, I can still enjoy listening at low levels on a great system without causing permanent damage to my ears.

I think we should draw a distinction between what sounds loud, and sound pressure level, as they are two different things. Also, the distortion as written about herein this thread (occurring in speakers as the volume is raised at and above 95db) is occurring in the *higher frequency band* (above 2K) as measured by sound stage. Those higher frequencies aren't necessarily the dominant factor when it comes to SPL.

In other words, I submit to the group that one CAN produce (hypothetical example) 100 db without much if any distortion, AND it may not sound (very) "loud". How so? Simple. Play music whose content is primarily lower frequencies, drums, organ, etc. If vocal and higher frequency sounds are absent, you'll have your high SPL, little if any distortion and it likely wouldn't be perceived as "loud" as if you had played a vocal track and then achieved the 100db on the basis of the vocals.

When I want to evaluate a system, including when critically listening to my own, I like relatively low volumes. If a system can move me with range, speed and detail at lower levels, I feel it is working well for my tastes. Once in a while, I will crank up one piece or another when I am in the mood, and yes that also gives me some information about the quality of the system’s sound. But I don’t think loudness should be necessary for most music, if the system is solid. Besides, I have hearing loss as it is, and I want to keep what I have left so I can keep enjoying it.

I agree with Kumakahn, I like to evaluate a system at low levels. If you need to crank it to get the frequency extremities its not for me as I listen at low levels. One thing I do notice about low level listening is the room plays less of a role as does vibration, so the effectiveness of feet etc. However, tweaks or cable changes etc seem harder to distinguish.