Most of what you will get from a better quality turntable will also improve the sound from your Sonos Fives or Sonos Amp and other speakers. Same with a higher quality cartridge, it will sound better on either speaker option.
I’d really lean to a pair of Sonos Fives, the turntable would connect to one or the other, Sonos will share the signal.
If you want more than the Fives can provide in volume then the Amp route is the way to go. If it is just the low end you are missing (even though the Fives do an excellent job there) adding a FULL Sub would be a good choice, I’d think (not have heard a system with one) the Mini Sub would not be that much of an improvement.
Do lots of shopping for your turntable and cartridge, that is not easy but knowing exactly what the performance of each will be can avoid regrets. Also make sure you buy the appropriate tools to properly set up the turntable, far too many out there are set up wrong and are providing far lower quality sound than they could with a few tweaks.
If you have the space and money the Amp and other speaker option is really attractive but make sure the spouse buys into the speakers taking over the front of the listening room. It has been 30 years since they left here but I still get complaints on my Klipsch La Scala’s size, 40x24x24 and 200 pounds each.
https://www.klipsch.com/products/la-scala-al-5
I use a pair of 5s and a full sub it works well with a turntable connected to one of the 5s
Hi
Nice to hear that you and your daughter are enjoying HER Project T1 turntable 
.
Our esteemed member @Stanley_4 gave some great advice even; if a bit frightening 
(IMO) per his helpful statement….
“Do lots of shopping for your turntable and cartridge, that is not easy but knowing exactly what the performance of each will be can avoid regrets. Also make sure you buy the appropriate tools to properly set up the turntable, far too many out there are set up wrong and are providing far lower quality sound than they could with a few tweaks.”
@Stanley_4 obviously has more than just a passing understanding on the subject to say the least. 
My point is that a lot of excellent turntables come pre-configured with matching cartridge and good specs right out of the box. IMO (which I own) the Project Debut Carbon Turntable Sonos Edition is an excellent example. It also has a few features such as an arcylic platter that is an upgrade for all turntables. To be honest I added a few more options such as
- Debut Alu Sub platter *
- Power Box S3 Phono (line conditioner) *
- Ground it E Base *
- Ugraded the Ortofon 2M Red cartridge to a Blue model
- Cambridge Duo Pre-Amp
One tool (borrowing from the @Stanley_4 playbook) that I use is a needle tracking force meter purchased for $60_USD. Interesting point the tracking force following the included setup directions for the Project Debut Carbon Sonos Edition was only a “hair’ off vs the adjustment made using the tracking force tool. Here, again the Project Debut Carbon Sonos Edition is great out of the box!
IMO...turntables made by a proven manufacturer in the $500 to $900 price range will be well received by most consumers and typically reviewed well by critics.
My complete setup of visible components (in case you’re wondering) is as follows:
- Project Debut Carbon Turntable Sonos Edition
- Sonos Amp
- Sonos Sub (full size)
- Cambridge Duo Pre-Amp
- Power Box S3 Phono (line conditioner)
- Ground it E Base
- Definitive D7 Bookshelf Speakers
- Morrow Audio_Speaker, RCA and Interconnect cables
If you prefer to go with a stereo pair of Five’s...that’s an excellent choice and reduces the number of components. I hope this was helpful and that @Stanley_4 doesn’t come looking for me.
Enjoy your new found love of vinyl!
* Project branded accessories
The all-in-one turntable packages are usually pretty good for their price point. I wouldn’t hesitate to recommend someone buy one as they are going to sound pretty good.
I would still carefully verify all the settings and adjustments, it isn’t rocket science but it is really touchy to get them spot on. Even if the factory shipped them perfectly set up the jostling during shipping can move something off the set point.
When I was personally buying (back when my ears worked better) I’d always pick and match the various bits to meed my desires, not something often met by the package deals. I’m sure I’d pay a premium for doing that but for me a big part of LPs joy was getting the best possible sound from them for as long as possible. The other part was the research and learning process, for something so simple looking there is a lot going on there.
Sonos has spoiled me, poke a couple buttons and music. For many the vinyl experience isn’t just listening, it goes way beyond the initial equipment purchase and slapping an album on the turntable, for others that is the whole process. Find your own sweet spot and enjoy it.
