While adding a second CA-2200 in a passive vertical biamp configuration MIGHT prove to be sonically beneficial on some musical passages, as Kr4 and Tls49 indicated it will not provide much in the way of a useful increase in power capability.
That is particularly true given the impedance characteristics of the 800D2, assuming they are similar to those of the 800D as it existed in 2011, shown in Figure 1 here. At frequencies between approximately 50 and 100 Hz, where lots of power is often required (for example, by drum beats), the speaker's combination of low impedance magnitudes and highly capacitive (negative) impedance phase angles will be especially challenging for an amplifier. Biamping two CA-2200's will provide a near zero increase in power capability at those frequencies, compared to what you have now.
Regards,
-- Al
That is particularly true given the impedance characteristics of the 800D2, assuming they are similar to those of the 800D as it existed in 2011, shown in Figure 1 here. At frequencies between approximately 50 and 100 Hz, where lots of power is often required (for example, by drum beats), the speaker's combination of low impedance magnitudes and highly capacitive (negative) impedance phase angles will be especially challenging for an amplifier. Biamping two CA-2200's will provide a near zero increase in power capability at those frequencies, compared to what you have now.
Regards,
-- Al