For the grouping becoming ungrouped, go to the Line-In settings for the Era 100 in the Sonos app. Under Autoplay, set the Autoplay Room to the room associated with the Era 100 and make sure “Include Grouped Rooms” is selected.

The rest of the stuff is a question for Pro-Ject.  I’m not a turntable guy, but what little I do know is that in general, high end turntables don’t lift or autoreturn the stylus, they are strictly manual.  Defies logic, but so does using 100+ year old technology to listen to music.  When all boiled down, turntables are more about esthetics and user participation that anything logical. 

Thank you.   I’ve set up the “Include Grouped Rooms” and will test tonight.    

​@AllenS4F you've pretty much hit the nail on the head as far as the T1 is concerned. It is somewhat annoying that it doesn't have an autostop on the tone arm, though I'm not so worried about the auto return. The sound is great with pair of Era100 set as a stereo set.

As ​@jgatie set up line in with any other speakers connected whilst using the T1, and it should avoid the whole issue of manually adding them back in after the T1 is turned on again to continue playback 

Pro-Ject does make automatic turntables. Thorens does as well. https://pro-jectusa.com/product-category/turntables/turntables-by-type/automatic-turntables/

Maybe do some shopping? Crutchfield has a nice selection and good information.

https://www.crutchfield.com/g_10500/Turntables.html?tp=75887

The T-1 is a good player, in the overall category it’s the more basic model but keep in mind Pro-ject tables run a very wide range from affordable to very expensive. You will be interested to find that many modern turntables generally don’t include many automatic features at all and focus more on sound and build quality than conveniences. Much to the inconvenience some. Modern vinyl listeners tend to be more concerned with the whole audio signal chain from stylus and needle, pre-amp, amp, to the end speaker more so than in years gone by when the general public listened to records and would forget they are playing. So the mechanics to do all that used to be a competitive feature from brand to brand, not so much anymore. 

I have the Sonos Edition Debut Carbon Esprit SB by Pro-ject and I bought this little tone arm lifter that keeps the needle off the record after it plays out by lifting it up. Works great. 
Audio-Technica AT6006R Safety Raiser

I have a similar setup, but an older Music Hall turntable and Era 300’s..it sounds ok, even running through a dedicated phono stage. Sadly, I think there’s quite a loss of sound quality though with Sonos’ hardware and and analog to digital conversion.. :/

Exactly, user participation, and ownership of the media. We “rent” access to media today with streaming services unless you have files on a server. The logic is, the act of playing 20 mins of a record at a time and listening to the presentation as intended is a lost past-time for many, and an unknown experience for a whole generation. So many new turntables are being sold to Millennials because they’ve never known actually owning music and listening to it in a physical form.  Modern artists are pressing vinyl concurrently upon release of new music to digital services and using fun colors and designs rather than black, so aesthetics are back baby! Cool album covers set on display, splatter and color vinyl designs, including a poster or booklet, gatefold covers…  and they love cassettes too.
As a Gen-X I bought a turntable because I missed hunting for music at record shops and listening to it intentionally on physical media. I am most times the oldest person in the shop when I go. This is a growing cohort. 

I would respectfully disagree about the ‘esthetics’ point - a good quality turntable and speakers can sound much better, more detailed, and more open than the modern Bluetooth/wifi speaker combo..but to your point there is certainly something pleasant about pulling out an album dropping the needle and reading the liner notes..

I looked at the Pro-Ject when I was shopping turntables but ultimately went with the Fluance RT85, which automatically shuts off the platter when the record ends.  The tonearm is then manually brought back to its cradle.  This is a good compromise, since the record and platter are stopped.  High-end turntables are manual because all the automatic features (and internal preamplifiers) require motors and parts that introduce vibration and/or sonic effects that diminish sound quality.  I am very pleased with my Fluance /Amp/Zen Pre-amp combination, which sounds great.   

I’ll jump in with my two cents….

I purchased the Pro-Ject Debut Carbon Turntable in Black (Sonos Edition). The comparable ProJect model can be found here. If you scroll down to add-on’s you’ll see that the Sonos Edition includes extra cost items such as the dust cover and upgraded Non-resonant acrylic platter. Another up-upgrade for the Sonos Edition is the Ortofon 2M Red cartridge. Those upgrades account for the $749 price for the Sonos Edition versus $599 for the ProJect model.

I upgraded my Sonos Edition to the Ortofon 2M Blue cartridge ($200) and the ProJect Debut Alu Sub-Platter ($179). All up I have $1,128 invested in the Pro-Ject Debut Carbon Turntable in Black (Sonos Edition) itself.

Additionally, I use an external pre-amp by Cambridge ($350), Ground it E Turntable Isolation Platform ($199), Power Box S3 Phono Power Supply Upgrade ($249), Definitive Technology D7 book shelf speakers ($600) and Sonos Sub Mini ($429). All powered by a Sonos Amp ($699).

Total investment to listen to my vinyl with Sonos: $3,654

My point being (outside of those mentioned by ​@tnprime ​@barcode ​@jgatie ) is that a manual turntable; which is typically belt driven, allows for more customization to expand/fine-tune the listening experience as it’s not so much about convenience. There are some who may spend the total amount I have invested on just a manual turntable alone; such as the model shown here. My pockets are no where near that deep. 

Bottom-line you didn’t reach the limits of Pro-Ject T1 Phono SB Turntable as a negative...to the contrary its doing what it was designed to do.

Returning to my Fluance -RT85 -- It includes an Ortofon 2M Blue cartridge, heavy acrylic belt driven platter, and all other essentials for $499.  That is why I bought it.  I use the iFi Zen preamp ($200), Wharfedale Denton 85th Ann. Edition speakers ($1,000), and the RSL 10S Mk!! subwoofer ($450), all connected to the Sonos Amp ($699).  I also have Roickville stands for the Dentons ($100).  So my total investment is $2,840 for everything.  It sounds fantastic.  The irony is that room acoustics and speaker stands can completely change your sound quality, regardless of how much you spend on electronics.   The Sonos amp lets me send music to other rooms where I have Sonos speakers and sub, but I never use it for that purpose because the sound quality just can’t match my “Stereo” system.  

Except there is no loss of sound quality in the analog to digital conversion.  Just ask the guy who didn’t know about the conversion and raved about his Fives “all analog signal” that “blows away” digital. 

I really wanted to build out something like this, in fact I wanted to go all retro-reconditioned gear but in my 530sq’ L-shaped apartment it just was too much physical gear. So I have to deal with “subpar” A/D conversion to my Sonos gear which actually suits the space perfectly and sonically is very good sounding to my taste. The better the source gear or more tailored to your liking the better the end result will always be. Alas, years of playing music and being an audio engineer has cooked my “hi-fi” ears anyhow so that has saved me so dough too. 
 

The ultimate solution to space considerations is a good set of headphones.  I wish the Sonos Amp allowed for them, but no bluetooth…..  

This is true, a good pre-amp and some headphones would be a good alternative for immersive and critical listening in a space as small as mine. Something to consider. 

​@tnprime 

If you were considering an external pre-amp here’s the one I use. The added bonus...it has a headphone jack integrated into the phono stage!  It’s also on sale for less than I paid two years ago.