We still don't know your budget, but you could try some tubes. The Jolida sounds very nice.
http://www.musicdirect.com/p-229971-jolida-glass-fx-tube-dac-iii-w.aspx?utm_source=googlepepla&utm_medium=adwords&id=71308431356&gclid=CjwKEAjw7O6vBRDpi7O-8OWSkwESJACNFsgxThCEcY9DXGYmAagWsez8JIcXj3GDZolpperYJ8rtrRoC0vDw_wcB
http://www.musicdirect.com/p-229971-jolida-glass-fx-tube-dac-iii-w.aspx?utm_source=googlepepla&utm_medium=adwords&id=71308431356&gclid=CjwKEAjw7O6vBRDpi7O-8OWSkwESJACNFsgxThCEcY9DXGYmAagWsez8JIcXj3GDZolpperYJ8rtrRoC0vDw_wcB