Reimer Tetons etc.., I almost went this route myself.. Seen the bigger models for around 2800 to 3800 tops used. However 15 watts will play them but controlling big woofers down to 30 hz is tuff anyway even at 95 db... You need current and a little headroom regardless of the efficiency rating, so I don't know that 15 watts would do it or not ,I would say 40 or 50 might be better for getting down super low, but then again you mentioned powered subs in the tower could be an option and then you would have something like a 100-300 watt plate amp taking care of that problem. Check link for an Idea, but they go cheap used normally.
http://cls.audiogon.com/cgi-bin/cls.pl?spkrfull&1161100439
http://cls.audiogon.com/cgi-bin/cls.pl?spkrfull&1161100439

