#5 is just the opposite of what your wrote. Your #1 states that room acoustics make up 50% of the sound. Where do you think the sound interaction comes from? The speakers. Since the speakers provide the other half of the interaction with the room, they are much more important than the front end.
So what will sound better:
1) A pair of (pick 'em - Dali Megalines/Dynaudio Temptations/Kharma Midi Grands/etc./etc.) with the $99 special Best Buy DVD unit playing CDs
OR
2) A pair of $500 Best Buy special whatevers with a P03/D03 Esoteric Player/DAC combo?
If you think #2, then I've got a bridge for you. Speakers ARE the determining factor in your reproduction chain. They have the highest utility factor (from economics). For every dollar spent on speakers, you get the highest return on music 'utils' than for a dollar spent anywhere else. The lowest return on your dollar are things like cables.
So what will sound better:
1) A pair of (pick 'em - Dali Megalines/Dynaudio Temptations/Kharma Midi Grands/etc./etc.) with the $99 special Best Buy DVD unit playing CDs
OR
2) A pair of $500 Best Buy special whatevers with a P03/D03 Esoteric Player/DAC combo?
If you think #2, then I've got a bridge for you. Speakers ARE the determining factor in your reproduction chain. They have the highest utility factor (from economics). For every dollar spent on speakers, you get the highest return on music 'utils' than for a dollar spent anywhere else. The lowest return on your dollar are things like cables.