I have also just acquired the S550i. It replaced a KAV-400xi. With only about five hours of use it is already head and shoulders above the KAV in all areas. This will, however, be the last Krell product I ever buy. Now that Dan D'Agostino has been ousted from the company he founded they are moving decidedly down market. The Mono and Duo amps they're hawking on their web site are all the proof you need. A real shame.