Audio Mirror has powerful triode SET monos with awesome midrange, tight deep bass, and sweet highs. And replacement tubes are not expensive. The 20 watt version should be plenty for your speakers. Email Vlad to discuss your needs and budget. Do not be discouraged by the MSRP - he often sells them new here for much less.
http://www.audiomirror.com/amps.html
http://www.audiomirror.com/amps.html