I just stumbled upon this thread and thought I might share something similar.
I have been using the Z5500 speakers for over three years now and I love the sound quality it can reproduce. Now you must understand that I am not an audiophile but have moderate experience with 5.1 speaker systems/packages. So I have been upgrading my PC slowly piece by piece and thought I would upgrade the surround system currently in place. When reading the following please keep in mind that I purchased the Z5500 package from amazon in 2008 for exactly £178.73 including delivery to my home address.
I started off by heading to Richer Sounds, a local audio/av shop and was advised to buy the following;
Denon AVR 1713 - £260
Tannoy SFX 5.1 - £200
I was told the above would be "more than enough" for someone like me who has a basic PC setup and it is also future proof as speakers can be replaced and the system can be used as a home cinema system. I went ahead and purchased the latter for around £460 but was extremely disappointed with the sound quality - The bass produced was just not enough and felt overall the entire system was much less powerful than the existing system I had in place (Z5500).
The next day I made my way back to Richer Sounds and explained the entire situation and was then advised for better sound quality I should purchase bookshelf speakers for both the front and back with an active subwoofer. Again, I am not an audiophile but went ahead with the advice I received therefore purchased the following;
Denon AVR 1713 - £260 (The same one I brought the first time, just adding it here so you can see the total cost for each build)
Cambridge Audio S30 x 2 Pairs - £259.90
Cambridge Audio S90 - £149.95
So this time around I spent around £670 and thought there is no way I could be disappointed, I mean surely for this sort of price the system must be at least three times as powerful and better sounding than the Z5500? Sadly not.. I plugged up the Cambridge Audio S30's into the Denon AV receiver and hoped for the best - Although the highs and mids sound incredible the subwoofer was still letting the entire system down! If I put the volume any higher than 75db the subwoofer would just start capping and dropping out. Needless to say I refunded this system and gave everything back to Richer Sounds.
I then spent a few days researching some good home cinema packages which led me to the next purchase, a Panasonic SC-BTT590EBK for £330 from amazon. The Panasonic looked promising with 1000 watts (peak) of power but the subwoofer just kept letting the entire system down therefore I started to give up on trying to find something that would beat the Z5500.. Does it exist?
I am currently using the Logitech Z906 from amazon for £229.90 which is reasonably priced considering how much I paid for the Z5500 four years ago. This system is a lot better than all the other setups I talked about but STILL does not beat the Z5500. A few differences I have observed between the Z906 and the Z5500 are;
The remote has been made too simple.
The control pod has been downgraded.
The subwoofer is a LOT smaller than the Z5500 and does not pack the same punch.
Z906 does NOT come with wall mounts.
Bottom line is I am disappointed with this system, granted not as much as the others I have tried but still disappointed.
Simply put, the Z5500 still kicks ass and I am yet to find something that can replace it. I understand that watts are not everything but after testing £600 systems I do not agree with this statement entirely - I believe the wattage is a good basis to start searching from. Personally I do not see myself as a "basshead" but after this whole experience I'm starting to think otherwise..
If anyone can advise on a kick ass system, feel free to leave a comment.