Jim and Dennis have said that SongTowers can be easily driven by any amp or receiver that delivers at least 50 wpc measured at 8 ohms.
My own experience with STs confirms that. I've heard them driven by various amps or receivers from as low as 35 wpc (an AVA tube amp) to as high as 225 wpc. None of them were obviously insufficient to drive them. When I first got them, I used a Denon AVR that was rated at 70 wpc. If I recall, that 70 wpc rating was also at 6-16 ohms, but it had no problems with the STs. Probably Denon's lawyers had more to do with that rating than their engineers

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As Ron already pointed out, the SongTowers with two midwoofs, will be more sensitive than the SongBird. But I think your receiver will not have any problems with either speaker.