HRT Streamer II disappointment

I recently  bought the HRT Streamer II after reading the reviews. I am disappointed with the sound, I have tried it via my Marantz NR1603 and Sennheiser cans from my Lenovo laptop and iMac. Using either iTunes or  JRiver's Media Center also tried various output modes in Media Center. Just to be sure I loaned it to a friend with and Alien ware laptop and Sennheiser cans with the same results.  Does anyone have any advice before I put it up for sale.