I have a pair of Sansui SP 2500x and Sansui SP 5500x speakers that need the perfect amp. I have the TU 9500 tuner and have a chance to buy the AU 999 or the AU 8500. What would be the best match for these speakers? I also have the SPX 8900's and the SPX 6000's. The AU 999 is $460 in MINT CONDITION and the AU 8500 is $500 in good condition.