No. Any analog line in, such as the RCA input on your Amp, will have the 75ms delay on any data. You’d be much better off ‘bonding’ the Amp with the PLAYBAR instead, which sets them up as one ‘Sonos room’. In that manner, your ceiling speakers become surrounds for the three front channels of the PLAYBAR. 

I’m not a fan of four surround speakers, but some use it, apparently. I’d think it muddles the surround stage, but I’ve never tried it, either. On the other hand, it seems like you’re going to use two, and the other two will only be turned up for music. Which is important, when playing music on the PLAYBAR, and the Amp bonded, the music would be in sync, the delay has been already paid, and the input isn’t via the analog line in. Or, if they’re two separate Sonos ‘rooms’, they’ll play music in sync. The 75ms delay is only reflected in the analog line in. 

If your intent is to have the four ceiling speakers play the same content as the ‘front channels’ of the PLAYBAR, rather than surround data, other than the 75ms delay, this would work. 

Thank you,

So to confirm :

-I won’t have a delay if amp and playbar are bonded for TV, only RCA?

-That being the case would you preferably bond playbar and via network cable via switch?

-how is the output from tv connected to the Sonos, would the preferred method be optical? I’m just in process of running cables, all cabling to go back to a network cab and would like to future proof it

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separately would you use play 1 speakers rather than shared amp/sonance setup in 3x toilet/bathrooms. Im thinking the only pro for amp setup in these areas are aesthetically, functionality wins with use of the wireless powered Sonos speakers for ease of individual control albeit restricted to surface mounted…?

Not sure how to answer your first question, without going into excruciating details.

There will be no delay between the PLAYBAR and the Amp, when the Amp is bonded in surround duty. This forces the Amp to be in the same ‘room’ as the PLAYBAR, and also turns off any other line ins on the Amp.

When the PLAYBAR’s room is grouped with other Sonos rooms, when streaming music, there is no delay between the rooms, when streaming the TV input, there will be that delay between the PLAYBAR’s room and any other room…but the Amp will remain in sync with the PLAYBAR, as it remains in the same ‘room’ (this will make more sense once you’ve done it, I suspect).

When I had two PLAYBARs, I never connected them via a switch with Ethernet cable. The bandwidth required was less than my WiFi could handle, so there was zero benefit in doing so. And yes, I occasionally would group my ‘kitchen’ speakers with my PLAYBAR, particularly during football games, so if I was there, I could still hear the commentary while cooking. But I didn’t have an ‘open’ floor plan in that house, the kitchen was a distinct room, the only chance to hear ‘both’ at the same time was essentially to stand in the doorway.

Oops, missed your second comment. 
 

Because I don’t due any critical listening in my baths (and yes, I can hear the guffaws and outright laughter from the peanut gallery now), I tend to have PLAY:1s in my various bathrooms. In fact, they sit on Sanus ‘over electrical plug’ (US link provided, but I think I got them either through Amazon or Best Buy) shelf, just to get them off the sink top. I do use the one in my master bath daily, when showering. It never gets too steamy, and I’ve never worried about them (or the PLAY:3 that used to sit on the back of my toilet). I probably wouldn’t want to put them in a sauna, or splash them much, but they have been working well for years and years. Since in that space, I don’t really need a full stereo effect, I’ve never considered that possibility, with third party in ceiling speakers and a Sonos Amp. I’m just not in that space long enough to think about it. A single PLAY:1/Sonos One/Sonos Era 100 is fine for that space.