The NVA AP10H headphone amp is recommended by UHF magazine ( uhfmag.com ), although the review is not available on the Net. The amp is available in kit or assembled form from Peak Audio in Nova Scotia.
http://www.peakaudio.ns.ca/cgi-bin/store/perlshop.cgi
http://www.peakaudio.ns.ca/cgi-bin/store/perlshop.cgi