Is Louder always Better?

Yes, Rhyno, tend to agree w/ your statements.
for me, louder is better and more palpable in sonic terms.
I am an avid Jazz Head, there is always a time to swing and swing loudly.

The same can be said for Rock n Roll (all genres). Clearly, this music was designed to be "amplified" or played loudly.

Lastly, classical music must be played loudly as well, to appreciate the many crescendo(s) to scale properly.

Thanks! for sharing- JA

+1, Rhyno, to all points regarding lowering the noise floor.
Louder is usually better but up to a point. Beyond that, your ears start to hurt with hearing loss and ringing over the long term.
Happy listening! J.

Rhyno,
I agree with some of your points & disagree with others...

the thing about home audio (digital particularly) is that as external noise is reduced, you are left w/ a purer signal....

after having read your entire OP where you "decoded" the meaning of "external noise", I now understand what you are trying to say & I agree. Really what you are talking about is "distortion" that adds to the existing noise floor thereby reducing the S/N.

....i consider those findings as evidence that 'louder is better' is a fine litmus test.

I'm not sure I agree with this - even tho' one's system might be low distortion, it doesn't mean that the volume should be cranked up to listen. Not all music sounds right with the volume knob cranked up. For example, unamplified/unplugged guitar music does not sound right when it's being played at overly high volumes. It sounds better & correct at a lower level that might be more representative of the SPL you might get in a hall with an unplugged guitar.
I've also found that when one's system is low(er) distortion then playing music at lower volumes is equally satisfying because the micro dynamics & macro dynamics are both present.
From the title of your post & your OP, I don't get that same feeling, which is a quite a big difference in my thinking & yours. You seem to think, write & prefer cranking up the volume to get the micro & macro dynamics which makes me want to believe that your equipment is not upto par to play at low(er) SPLs & still deliver the micro & macro dynamics. If that's the case, you still have more work to do.....

i've found that external noise removal is a function of 3 efforts, all of which are equally important:
1) power conditioning
2) vibrations
3) room acoustics

I think you skipped a big step & put the cart before the horse - one's electronics & speakers. Before one goes onto making improvements to your above 3 cited items, one needs to ensure that the electronics + speakers are low distortion otherwise one will simply end up revealing the flaws of one's equipment & be limited by the same.
In your "context" para you did cite not creating imp mismatches, avoiding clipping, having suff output power, not disconnecting tweeters, etc but those conditions do not include selecting electronics + speakers with low(er) distortion.
Again, by noting that "louder is better" for you, you have some work to do in upgrading/replacing your electronics &/or speakers with lower distortion equivalents.

In my experience as distortion is lowered and S/N ratio increases ,listening can be done at lower SPL levels and is very engaging and involving. There's less need for higher volume in order to enjoy music reproduction. True resolution reveals nuance and dynamic gradients/emotion at a lower listening volume. This improvement means cranking the sound is not needed for compensation due to lower resolution systems.better resolution means less volume is required.
Charles,

source material quality always matters, as do electronics. but folks spend fortunes here and never get this right, ergo my post. a sony receiver will never amount to much due to its inherent S/N ratio, but thats self evident i think.

in context of my premise that louder is better, its always in relation to 'fatigue', and not a function of enjoyment at a particular volume (which is more plausible as S/N ratio improves). you simply aren't as limited by the noise (via fatigue) when reaching for the volume setting. the louder you can listen without fatigue, the better your system is, given some selective assumptions as defined originally.

good listening folks