1)Qinpu - A-6000 MKII - Integrated /Headphone Amplifier
2)Sony SS-B3000 Bookshelf Speakers (Pair, Black)

If you want to spend more

3) V-DAC II ( Digital-Analog-Converter )

I added the V-DAC II, can not feel obvious efects. But 1 and 2 makes big difference. 1) + 2 ) about $400.