I have a Sony Blu Ray all in one surround sound 5.1 speaker system (front 3 speakers and sub are wired, rear 2 speakers are wireless) that has been perfect for six years.  It just recently started cutting out the sound for a few seconds once every minute or so to every speaker.  It makes the show un-watchable because it is so annoying.  I know the issue is with that system because I can turn it off and listen thru the TV speaker and it works just fine without cutting out.  Nothing has been moved (thus loosening a connection), nothing has been disconnected, nothing has been changed.  All connections have been checked for tightness and are good.

I'm stumped.  All I can figure is that the guts just went bad and it needs to be replaced.  Do you guys agree or am I missing something obvious?  Anything else I should do before I replace it?

Your thread title says "surround sound speakers."  So it's only the rear speakers that are cutting out?  Does 'wireless' mean bluetooth?  If so, maybe pair an inexpensive bluetooth portable speaker to one of the channels and test.

Sorry, I could've been more specific.  All speakers cut out at the same time.
The system is Sony model number BDVN790W.  And I've looked, but I can't find if the rear speakers are bluetooth or something else.

Unfortunately that sounds like how my surround started going out.  It didn't have a wireless component but sounds similar to what you're experiencing.  I found that it started cutting out after the system had warmed up for awhile.  It would be fine at first but then it

would start malfunctioning before the first movie was finished.  Got progressively worse so it was and easy call to make.

Reading the manual, it looks like the surround speakers use a separate surround amplifier that is connected with to the main box with optical cables.  Then a wireless connection is made from the surround amp to the surround speakers.

Page 40 shows advanced setup instructions for that.  The wireless connection can have problems with interference from other wireless devices in the area.  Or there could be a problem with the optical cables (unlikely.)

That doesn't explain why ALL the sound is cutting out, though.  Maybe the system has a feature that mutes all the audio when the connection is lost to the surrounds.  Or maybe the main box preamp is just malfunctioning.

Hope you get it sorted out.