Most well built recievers should handle a reasonable 4Ohm load without much difficulty. Ohm ratings are fairly misleading as impedance is never static. In reality, the impdance of the speaker will vary greatly depending on the frequency it's trying to reproduce. As such, quality recievers are already built to handle these variations and output the required current. What I would recommend is to play them quietly at first and build up the volume to see if you hear any distortion or if the amp begins to overheat. These are signs that the amplifier is unable to output the necessary current. If you experience either of these symptoms at reasonable listening levels DO NOT use the speakers as they could damage the amp. However, I would guess you'll be absolutely fine at normal volume.
Edited by Iceman23 - 6/17/11 at 11:31am