The reason for the split is simple, and the reason they can’t fix it is even simpler - All the S1 only devices have miniscule amounts of RAM and storage, and the firmware required to even recognize new S2 devices, never mind run the S2 features, is too big for the 32 MB RAM/storage on the S1 only units.  If an S1 device can’t recognize an S2 device on the same system, there’s no way they can play together.

So you see, unless you have a way of making 32MB larger, there is no way to get them to play together on one system.  

Also, are you using the same Amazon Music account for both S1 and S2?  If so, that may explain the stopping and starting.  Because I’m pretty sure Amazon only allows playback on a single system or standalone device at a time. 

I‘ve been seeing playback issues from Amazon recently, pretty sure it is an Amazon issue though.

You could wait for an issue and submit a diagnostic to have Sonos support look at it. You do have to ask and provide the Diagnostic number.

Thanks Jgatie and Stanley_4 for your help.

Regarding the lack of memory space.  I get it.  What I don’t get is that there doesn’t seem to be any interest in finding a way to retrofit S1 devices with expanded memory if that’s the only issue.  I’d be willing to ship my arsenal of S1 devices to Sonos or a 3rd party service partner to upgrade my devices.  That would probably be a more cost effective solution than spending big dollars to replace my Play:5’s, Subs, Connects, et.al. with the expensive new S2 versions.  

If retrofitting is a feasible and viable solution, is it possible Sonos just doesn’t want to bother with it?  Easier for them throwing up their hands and saying, sorry for that, but you can always buy new stuff with more memory from us. 

Regarding concurrent use of Amazon Music, I need to get a better understanding of what you’re suggesting. 

I do have both S1 and S2 “DEVICES” running on the same S1 controlled network.  I don’t run an S2 controlled network.   Please also consider that my problem isn’t that it doesn’t stream.  The problem is that it doesn’t stream correctly.  I would think if Amazon has a 1-system governor on their service, then I  wouldn’t get anything streaming at all if Amazon thought I was trying to run their service on 2 devices simultaneously.

Regarding opening a support ticket.  I’m open to that.  I’ll give it a whirl.  Why not, right?

My guess is that it’s not a particularly viable solution. If the original design had started off with the concept of plug in parts, it might have been more sensible, but I suspect everything is pretty much soldered together, and the manual labor to update a device would be higher than the original cost of the device. I could see a memory update, between the cost of the chips and the labor, topping $300, and woudn’t it be better to buy a newer one at that point? 

Not ecologically speaking, for sure, but until recently, that hasn’t been part of the thought process of Sonos. Supposedly, that’s changing, and hopefully newer devices in the design process might have that concept built in. 

I’ll leave the rest to @jgatie and @Stanley_4. 

Amazon Music Unlimited streams losslessly at 1 - 1.5Mbps approx. One would guess your other services are lossy at a fraction of that bitrate. 

Your local wireless network is probably choking somewhere when a decent number of rooms are grouped. A Sonos system diagnostic should reveal where.

Here’s something else that occurred to me regarding Amazon requiring single thread.  I have an S2 Boost hardwired to a Comcast Xfinity Xfi Gateway.  The Sonos mesh network is built from a wired connection to my router.

Retrofitting means retrofitting new components to almost 20 year old standards.  I kept a VAX Alpha based OLTP system running for 10 years past its expiration date, so I personally know what that's like.  It's difficult to impossible, and very expensive.  The fittings don't match, the processor sockets don't match, new standards like SD cards don't work with PCMCIA without expensive adapters, etc., etc.  And like Bruce said, if the components are soldered to the board, it is specialist labor intensive. Between shipping, parts, and paying the specialist to do the work, it's probably less expensive to just give away a comparable S2 device, which would bankrupt Sonos.

You can’t just replace chips either, you’d need to replace the main board to add the needed traces for the expanded memory addressing.

So unsoldering all components, testing them to find the ones that didn’t survive that. Soldering the salvaged and new components to the new board, by hand as the usual automated devices are fed components on a reel. More testing.

I’d bet the basic upgrade labor would cost more than a new Sonos. Add in the cost of the new chips, assembly of the case and shipping both ways and it is even worse.

Sonos does sell some refurbished units, the level of repair they go to isn’t public. Sonos does not offer a repair service either. If neither of these are viable for Sonos upgrades likely aren’t either.

I have modified main boards to correct design errors like missing or wrong traces and even done very well they are never as reliable with the jumpers compared to a unit with the correct traces. We’d do emergency surgery on small pre-production batches to get them out the door for testing but would never have considered shipping something like that as a production or refurb unit.

OK,not viable, but sad.  People in my position that are stuck between a decision to discard thousands of dollars of equipment and buy thousands of dollars of replacements or live with obsolete hardware are doomed to suffer one way or the other.  

I won’t a buyer that’s party to the Sonos upgrade trap.  My Sonos buying days are over.

Thanks you all for all of your expert advice. 

Question for ratty.  Did you mean Amazon lossless streams at 1-1.5 gbps?

I’m going to unplug several speakers and see it that has a positive effect on my Amazon Music issue.  Not confident about that solution.  

1 Gigabit per second? Er, no. 1-1.5Mbps, in rough numbers.

16/44 stereo PCM requires 1411kbps (plus overhead). After lossless compression (FLAC) this ends up in the approx range 600-1200kbps depending on the music complexity. For illustrative purposes I picked a round number at the upper end: 1000kbps, hence 1Mbps.

Since Amazon can also stream in 24-bit I added 50% to arrive at the larger figure of 1.5Mbps. As it happens this can be ignored in your case since S1 can’t support 24-bit.

Why don’t you just submit a diagnostic after a dropout incident, note the confirmation number, and call Sonos Support? They’d be able to identify packet loss and the likely cause.

Found this info in PC Mag regarding Amazon Music Unlimited and Ultra HD.

Now, all Amazon Music Unlimited subscribers can enjoy more than 75 million songs in HD quality (up to 850Kbps, 16-bit at 44.1kHz) and more than 7 million songs in Ultra HD quality (up to an absurd 3,730Kbps, 24-bit at 192kHz). 

You can only listen to Amazon Music HD via the Android, iOS, macOS, and Windows apps; you cannot stream the high-quality music via a web browser. On the upside, the apps have quality indicators to show when you're listening to an HD or Ultra HD track. You can read about the Ultra HD hardware requirements and general compatibility at Amazon's Music HD page.

Obviously not accurate, as it makes no mention of playback via Sonos. Old article perhaps?