When I owned a Unico the tubes I liked the best were Telefunken. Radiotechnique might work for you. The addition of Herbie's HAL-O tube dampers made them more refined and focused and is recommended.
Check out this Search link on AudioAsylum.com for posts regarding the Unico and tubes: http://db.audioasylum.com/cgi/search.mpl?forum=tubes&searchtext=unico
Good luck.
Check out this Search link on AudioAsylum.com for posts regarding the Unico and tubes: http://db.audioasylum.com/cgi/search.mpl?forum=tubes&searchtext=unico
Good luck.