This thread is dead?

Hopefully not, for those who are still using the Z5500 as main speakers. 

I often use it before going into hifi/passive speakers/amp around 2017, which then my Logitech Z5500 became less used and paired with my PS3.  I still turn it on once in a while, maybe few months once.  But this year, I noticed the satellite speaker sounds became 'soft' ... took off the protection cover, was dismayed to find that the driver cone rubber/foam got holes ... not eaten by insects I think, just became dried and brittle ... only the centre speaker still ok ... maybe it was 'used' more?  The room I put it in isn't exposed to bright sunlight, it's quite dark in fact, but can be hot (on 2nd floor).
Anyway, the only way to fix the satellite speakers (all 4) are to refoam them.

Replacement for Z5500 ar    ... imho, the similar set of speakers that last time often mentioned can fight Z5500 is Edifier S760D (RM2K+)
https://www.edifier.com/my/en/speakers/s760...gaming-speakers
but like Z5500, it can only support the basic Dolby Pro Logic II, Dolby Digital 5.1 and DTS 5.1

Recent entry level HT AV amp with 5.1 passive speakers+sub-woofer (mix n match your favourites, change/upgrade if spoilt) should be able to support more formats, including Dolby Atmos but maybe need RM5K+ budget (or just RM2.7K for starters), but more worth it since you've experienced Z5500 before, and maybe now wish for something more.