As a former Z5500 and current S760D owner, since May of this year, I strongly suggest to anyone considering this same transition to absolutely go ahead and pull the trigger!
This 5.1 system is in another league compared to the Z5500, trust me! I did expect a difference, but damn... the S760D honestly exceeded my expectations. This system sound very neutral and much MUCH cleaner than the Logitech, the biggest difference is in the mids and highs. Compared to the tweeterless Z5500 satellites, details you didn't know were there can be easily heard, the bass is even thicker and more "robust" so to say, while not overpowering the rest of the range, it's very nicely balanced.
Only issue is the oddly shaped remote, which is very elongated and wobbles when pressing buttons on a flat surface.
Also the market for used Z5500's is pretty much still alive, so you could easily sell them off. Believe me, you won't regret this purchase :)
andydsmFormer Z5500 owner here too. For that price, I feel it would be really hard to pass up a solid 2.1 system for cheaper unless you're really wanting a 5.1 gaming experience. Looks nice though!
treal512surround gaming is basically dead. Even games that offer "surround sound" gaming are just upscaling stereo and using some tricks to make it sound like surround. True positional audio died about a decade ago when they killed alchemy/A3D. You're STILL better off with a solid 2.1 system unless you want to specifically watch movies, and then you're going to want an actual receiver that can decode audio formats outside of DTS, most likely.
For roughly the same price as this you could pick up a pair of kef Q100s and an emotiva a100 mini X, and have a much better overall experience. You can always build or roll a sub in later, or even use the q100's as satellites in a surround system.
EldestructoI bought my S760D system locally (I'm in Europe) for around $650 an year ago. Sold the Z5500 for $220 ish, couldn't be happier with the system :)