does it matter what speaker you plug turntable into for audio quality?

To see (hear) how it sounds you could remove the era 300’s and Sub from the Arc and set them up as a stereo pair with the Sub bonded too. Then try the turntable and decide if you like it. Fives are arguably better for stereo music duty, but I think the Era 300’s are a close alternative. 

Thank you, yeah I have tried that and it does sound better (300s and sub as stereo), however that would remove  the whole tv setup.

kind of a shame that in order to get the sound quality my tv now has, I’d have to buy that whole setup again (minus arc) in order for my vinyl to have that same sound quality… I assumed connecting everything in the app made it so all speakers sound at their best, which isn’t the case.

Playing vinyl, you’re expecting stereo, from two speakers located in front of you. Stereo separation from a soundbar will rarely be as good as from two separate (and more widely spaced) speakers. When the music is also playing from surrounds located behind you too, it muddies the sound you’re expecting. 

Yeah, that makes sense now I think about it. Maybe it was too easy to think ‘more speakers equal better music’.

what would your advice be? I’m considering disconnecting the turntable from Sonos to get the quality I expected back and getting regular speakers again.

thanks again  

The other Sonos setup would be an Amp with “conventional” speakers. Going that route, you can still group any combination of rooms so you can have whole-house music for parties. 

Cheers, thank you for helping me understand!

Just to be certain, you do have a pre-amp set up on that turntable? Either an internal one, with the output set to line, not phono, or an external one?

This is a good post about it, with lots of links.

If you think that compression has been applied, check here. Make sure that your stylus force is correct. Generally, things sound better when set near the upper end of the recommend range and, counterintuively, record wear is usually lower too. Tracking too light will cause significant wear with each playing, plus it doesn't sound best.

I do, however it’s always been a budget choice. I didn’t know about a difference in phono or line in output. 
 

its an analogis easy phono preamp with no option to change output.

Yep have done! Thx. Stylus force I check every now and then, that looks good.

Whilst it’s right to check these things, the op was questioning sound quality through different speaker/speaker combinations - one of which they particularly like - so the turntable must be reasonably well set up. 

On the pre-amp question, ​@Rutger199876, either you need one or you don’t. You are using one; there’s no switch. Some turntables put out a low-level signal that needs a boost in power, which the preamp delivers. Other turntables produce the amplified signal. Some turntables offer the option to output either signal so that folk with a particular preference for a specific preamp can use it regardless what turntable they use. 

Making phono preamp selection even more fun is that there are two types MC and MM (Moving Coil and Moving Magnet) that are incompatible. Some phono preamps include both and let you select either, handy for folks that use both types.

There are a lot of other turntable adjustments other than tracking force, a good turntable focused forum would be worth a visit to get a basic education on that and check your settings.

I’m no expert on Sonos Line-In, not having used it for several (OK, many) years now but as I understood it once the line-in signal is accepted into the Sonos system it is passed to any other Sonos without any loss of quality. Sonos doesn't publish specs on the line-in connection hardware so there may be quality issues there.

But, to further that, all Sonos line ins are the same. There is no difference beyond form factor. It’s controlled by the software. 

To hear how it actually sounds, you can remove the Era 300s and the Sub from the Arc and set them up as a stereo pair with the Sub bonded to them. Then try the turntable and see if you like the result. The Fives are often considered better for dedicated stereo music, but the Era 300s are a solid alternative.

en.community.sonos.com/home-theater-229129/connecting-my-playbar-and-sub-4-6932653