StonedTemplePilot,
There's a trade-off relationship between immediacy and richness. The more dominant the first-arrival sound, the more immediate (front-of-the-hall) the presentation. The more dominant the reverberant energy, the more rich and ambient (rear-of-the-hall) the presentation. Room acoustics, speaker positioning, and speaker radiation characteristics come into play here.
In my opinion, the characteristics that would give what you're looking for in a loudspeaker are a slightly downward-sloping on-axis response and smooth power response along with a somewhat narrower-than-normal radiation pattern. You also want a speaker with good dynamic contrast (minimal thermal compression), as this correlates well with liveliness at low volume levels.
If you listen from more than 5 feet away from the speakers, most of the sound energy that reaches your ears is reverberant sound. A key difference between live (unplugged) and reproduced music is this: Live instruments produce natural-sounding reverberant fields, but most home sound systems don't. For example, listen to a piano from the next room, through an open doorway with no line-of-sight to the instrument. All you can hear is the reverberant energy, but it sounds totally natural and convincing. On the other hand, very few sound systems will sound real when listened to from the next room, and this is because they do not generate a spectrally (and dynamically) correct reverberant field.
Now the idea is not to have a system that you can listen to from the next room - the idea is to have a system that replicates as close as possible the sound field of a live performance. And in my opinion this cannot be done without getting the reverberant field right.
In your listening room, you want a strong, diffuse reverberant field that ideally begins to arrive as long after the first-arrival sound as possible. You do not want an overdamped room, and most home listening rooms are overdamped (carpeted, with overstuffed fabric furniture). Large plants and lots of wooden furniture are good for diffusion, or you can get dedicated diffusors. Since most of the sound energy that reaches your ears is reverberant sound (assuming you sit more than 5 feet away from the speakers), in my opinion it makes sense to start with speakers and proceed to room treatments that give you a natural-sounding reverberant field.
Regarding amplification, SET and OTL amps along with low feedback Class A solid state amps have distortion characteristics that are in harmony with how the ears work. The commonly used total harmonic distortion specification has no useful correlation to how we perceive sound - the amplifier industry has been measuring the wrong thing for years.
Duke
dealer/manufacturer