The z5500 is good if your on a budget, be rest assured its no where near the performance of the other two. I have personally heard it, the sound is very muddy...the subwoofer overpowers everything else in that and it would have been nice if it wasn't for the sub to actually sound boomy instead of creating real bass! Plus its old and not future effective, you invest in either of the other 2 and you will have atleast 6-7 years and more before you feel the formats are old! Do remember when you try to push mp3's through the logitech it would sound decent but the other two will simply feel bad, until you choose the prologic mode....the high end receivers love uncompressed audio, the more your streams consist of that the more you will smile! dts hd dolby master audio etc are supported by the other two and they are far superior to old formats! MKV's and bluray rips have those streams and you can fully utilize them!