I have a pair of Epos ELS-3s and am looking to upgrade to the 5.1 system (4 ELS-3, ELS-3C & ELS Sub). The problem is, these speakers have an impedance of 4 ohms (nominal). I am having trouble finding a receiver that is rated at 4 ohms that isn't twice the price of the whole Epos 5.1 setup, which MSRPs at ~$1500.

Any suggestions? Should I look to power via separate pre-amp/amp rather than using a receiver? Specific product names/models would be most helpful!

Here's some quick info on the speakers:
ELS-3
Power Handling 100 Watts Max
Frequency Response 65Hz - 20kHz
Impedance 4 Ohms Nominal
Sensitivity 87dB/1 watt/1 metre
Amplifier Compatibility 25 - 100 Watt

ELS-3C (center)
Power Handling 100 Watt Max
Frequency Response 65 Hz - 20 kHz
Impedance 8 Ohm nominal
Sensitivity 87dB/1W/1m
Amplifier Compatibility 25 - 100 Watt

ELS Sub
Power Handling 300 Watts
Frequency Response 20 Hz to 150 Hz with high and low filter
Impedance 4 Ohms
Sensitivity 89dB per Watt
Amplifier Compatibility Built-in
Configuration 10" Bass Driver