Big 2 channel Amp OR Smaller 6 channel and TRIamp?

1. Depends on crossover points.
The 50:50 energy point is about 350hz.

2. Can the amp make full power with 6 channels driven, or more likely, somewhat less than rating.

Depending on cross over point and amp permitting, you may even want to bridge a pair of channels for the lows and simply biamp.....

For the KEF Reference 203.2 (could not easily find the specs for the 203.1), the LF crossover is 300Hz in these speakers and sensitivity is 89dB/2.83v/m so the woofer eats half the power and the power rating is 50-200w. So, I would guess, again, that the 300w amp would be the more effective solution.

Kal

Kal.... What do you think about my observation (based on measurements) that the equal power frequency (350 Hz or thereabout) is not what natters? I have found that with a real music signal the peak voltage swing requirement for the higher frequency signal is only met by a power amp with substantially greater power rating than that based on equal power.

Can you explain how you reached this conclusion? AFAIK, the current (and power) required is a function of voltage swing of the source and the impedance of the load.

02-18-12: Eldartford
I have found that with a real music signal the peak voltage swing requirement for the higher frequency signal is only met by a power amp with substantially greater power rating than that based on equal power.

No question about it. As we discussed in this thread, in a properly gain matched passive biamp (or triamp) arrangement there is no division of voltages between the different amplifiers, just a division of current and power. If there were a division of voltages, it would mean that gains are not properly matched, and frequency response flatness would be thrown off.

(In saying that, I'm neglecting small voltage differences that may occur under properly gain matched conditions if a tube amp having significant output impedance is involved, AND if the speaker presents significantly differing impedances in the frequency ranges handled by the different amplifiers).

Concerning the OP's question, I would expect that which configuration would provide better overall results will depend on the specific amplifiers that are involved. But fwiw my instinct is that it is generally best to go with a less complex solution (Option A in this case) than a more complex solution (Option B in this case), unless there is a clear reason to do otherwise. Or unless there is an opportunity to try both approaches, and compare.

Regards,
-- Al