Markus -- I couldn't find an impedance vs. frequency curve on those speakers. I did find this descriptive information, which might be of interest:
http://www.audiokarma.org/forums/showthread.php?t=70808
The fact that the low frequency driver has no crossover elements in series with it lessens my confidence that its impedance does not drop below significantly below 8 ohms over a significant part of the spectrum. So I would not hook them up in parallel to the G-9000.
If all four speakers are the same Presidian model you could try wiring them in series, and see how you like the sound. The main sonic consequence of the series connection, given that the speakers are identical, would be to bass damping, but they probably don't have much bass response anyway. Also, the maximum power available to each speaker would be reduced substantially, perhaps to 25% of the amplifier's capability (the nominal 160 watts reduced to 40 watts), because each speaker would see only half of the voltage being put out by the amplifier at any given instant.
Alternatively you could add a second amp as Bob has suggested, or else purchase an amp known to be able to drive low impedance loads. The older Adcom models (GFA-535, GFA-545, GFA-555, GFA-565 etc.) would do fine, and are not expensive. Also, probably any amp that can be strapped for use as a monoblock would do well, because a bridged mono amp sees a load equal to one-half of the speaker's impedance, and therefore presumably is designed to drive low impedances. Bridgeable amplifiers usually specify that nominally 8 ohm speakers should be used in bridged mode, as opposed to nominally 4 ohm speakers, btw.
Hope that helps,
-- Al
http://www.audiokarma.org/forums/showthread.php?t=70808
The fact that the low frequency driver has no crossover elements in series with it lessens my confidence that its impedance does not drop below significantly below 8 ohms over a significant part of the spectrum. So I would not hook them up in parallel to the G-9000.
If all four speakers are the same Presidian model you could try wiring them in series, and see how you like the sound. The main sonic consequence of the series connection, given that the speakers are identical, would be to bass damping, but they probably don't have much bass response anyway. Also, the maximum power available to each speaker would be reduced substantially, perhaps to 25% of the amplifier's capability (the nominal 160 watts reduced to 40 watts), because each speaker would see only half of the voltage being put out by the amplifier at any given instant.
Alternatively you could add a second amp as Bob has suggested, or else purchase an amp known to be able to drive low impedance loads. The older Adcom models (GFA-535, GFA-545, GFA-555, GFA-565 etc.) would do fine, and are not expensive. Also, probably any amp that can be strapped for use as a monoblock would do well, because a bridged mono amp sees a load equal to one-half of the speaker's impedance, and therefore presumably is designed to drive low impedances. Bridgeable amplifiers usually specify that nominally 8 ohm speakers should be used in bridged mode, as opposed to nominally 4 ohm speakers, btw.
Hope that helps,
-- Al