in my limited experience, it isn't the input type that determines the amp size so much as the class of the amp. ie: class a/b amps need to be larger for all the analog FET's and required heatsinking, where class d amps, depending on the amount of power, can be dramatically smaller.
The ultimate is Direct Injection. No analog ears etc - just direct injection into the appropriate brain cells.
Best thing is - you won't go deaf. (No more grasshoppers or cicadas - yay!)
soundman - I still don't get the Ohmage as related to higher power. It is easier getting more power with higher voltage than it is with higher current - ie, increase the Ohmage.
I certainly don't recall low-Ohmage speakers in the old 40kW music PA systems - I think they were 8 Ohm as were speakers in Marshall and other guitar & music amps.
Sute, they had the luxury of AC voltage (110-240VAC), but with the advent of SMPS for 12VDC systems, that is now irrelevant.
I'm sure a 1kW sub at 4 Ohm would sound better than 1 Ohm - the only difference being a 70V rail as opposed to 35V rail at 4x the current (and 16x the heat; smaller filter caps, etc).
part of your problem is that your still trying to make sense of the numbers. take a step back and look at only the output numbers-- that is what the 'draw' is. the majority doesn't care about the parameters in which those output numbers were created, they only care to know that "their amp outputs more power then the other guys."
it doesn't matter that a cheap car audio amp had 120v power input, and 20v rca audio input to achieve a erroneous '20,000watt!!!' rating-- all that matters to them is that power rating number on the box--and they see that the power rating goes higher with less resistance. period. at this point there is no car audio company that actually describes the loss in clarity that occurs while stepping down the speakers physical impedance--and i say it that way because the physical speaker impedance is slightly different the amp load--the impedance of the speaker is what affects it's sound quality more-so then the end-load at the amp. i could connect 2 mis-matched 8ohm speakers that have a end load of 1ohm at the amp, of course that works out to be a weird efficiency conundrum(the speakers are efficient, but the amp might not be at the resistance rating).....
that is the part that frustrates me so much with this stuff -- the public's misperceptions of audio...
the pro audio area really doesn't go with speakers any lower then 8ohm because of the physics(that i am sure you already understand). with a 8ohm speaker, the efficiency is higher, meaning that 40w of audio power is just as powerful as 80w of audio power into a 4ohm speaker--because there is more copper within the magnetic gap, and that allows the power to be more effectively transferred into a audio signal. that better efficiency means that the audio is clearer.
so with much of the pro audio area focuses primarily on vocal clarity, and it only makes sense that they would use higher efficiency speakers in the 8/16/32ohm rating because it allows voices to be easier to hear because there is so much more control over the speakers finite movements.
Thanks - I see what you are saying.
Yes, we are BOTH frustrated by misperceptions of audio .... and power, batteries, electrickery, and reality.
I was coming from the technical POV that if you can get x-Amps at 1 Ohm, then it should be easy to get x-Amps at 4 Ohm and hence have FOUR TIMES the power.
A 10kW 1-Ohm sub is a 100V rail at 100A.
Make that 4 Ohms at 400V for 40kW at 100A.
The extra insulation is negligible compared to the copper for 100A, and many components can be rated for the higher voltage.
Both voltages are fatal (both are classed as HVDC and require licensing).
That's an extreme example (a 10kW single speaker) - it's even easier with smaller 1kW speakers (32V DC) - even if only doubling output to 2kW (64V DC) to remain under licensing requirements (or does the +ve to -ve rail count?).
So it's the same 'ol same 'ol.
People "think", therefore the industry takes advantage.
Because an audio guru starts using caps, everyone does. That same guru later recants and explains the faulty logic and application, but too late, the ignorant continue and the industry is all to willing to supply - after all, the alternators and batteries will still sell after users figure their mistake. (Mind you, the now existing cap usage to protect AGM batteries is a different issue, but that's NOT to prevent dips, though that is an outcome.)
I'm surrounded by such people here! The number that insist on expensive dc-dc converters to "properly charge" their secondary/remote batteries, or voltage-sensing battery isolators for typical automotive alternators...
I should jump on the bandwagon... sell my double-5c "voltage increasing" diode for over $20, market the UIBI-2 for $99.95, etc.