Sonos Amp: Line-In Autoplay Won't Turn Off with Vinyl Setup

Okay for sure - the source level currently set at 1 out of 10. I’d like to play around with it, but unfortunately I’m hearing a lot of clipping on vocals/treble if the Line-In Source Level is higher than 1, which seems bizarre to me. Using an Ortofon 2M Red cartridge.

Comfortable vinyl listening on the volume bar is around 45/100, so I don’t need to turn it up crazy loud with the Line-In level at a measly 1/10. But why does my Line-In volume need to be so incredibly low to avoid clipping? 

Alright - just got off the phone with Sonos support and they told me that if I’m keeping my Line-Out Level at 1, there’s way too much power coming from my turntable + phono preamp setup that’s being funneled into the Amp and I should use a Port instead. 

Great…..haha

The Line-In sensitivity of the Port is the same as the Amp.

If your Amp is not auto-stopping playback after you lift the needle, suspect a grounding problem. Inaudible ripple could be preventing the Amp from detecting silence. 

Make sure the cartridge mode on the phono amplifier is set to MM rather than MC. If it’s currently set to MC, make sure the unit is disconnected from the power supply and Amp before you change the mode to MM.

Thanks ratty. That’s very strange then, I have no clue as to why I could go from using 10/10 on my Port to 1/10 with the Amp and the preamp. Ground wire from the turntable is grounded to the terminal on the Phono Box.

Any suggestions regarding power supply/surge protectors/etc are welcome. Or is this something in which I need to swap out my vintage turntable for a newer one? I’m out of ideas and worried that I could fry this new Amp.

Thanks for the tip - it’s set to MM.

Have you perhaps got the Pro-Ject Phono Box DC preamp switch set for MC cartridge by mistake?

edit: I see now that’s just been answered whilst I was typing my post - please ignore.

This seems a little odd to me -  Have you considered swapping the setup back to the ‘Port’ to see if  everything is then okay again?

In a online review of the Pro-Ject Phono Box DC prep-amp here I note that it mentions this:

Ultra-low Impedance Output Stage

The Pro-Ject Audio Phono Box DC is an audiophile grade phono preamplifier. It has a low output impedance that makes it incredibly easy to drive even the most delicate of speakers and doesn’t require any power amps or amplifiers at all, making this compact unit very portable. The three digit Ultra-low Impedance Output Stage provides crystal clear sound with no loss in detail whatsoever.

Yep, I just switched back to the setup with the Port to see if anything would change. I added the Phono Box this time, plugged into my Onkyo receiver into the CD inputs. So it’s turntable + phono preamp + receiver + Port.

Put a record on, turned up the Line-Out Level to 10/10, and no clipping whatsoever with this setup. I continue to be stumped!

I got the Amp in the first place to simplify my setup and to rid myself of my heavy Onkyo receiver, but this Receiver + Port setup seems more reliable right now :( 

Okay, but what happens if you omit the Onkyo Receiver and just setup turntable —> preamp —> port?

What speakers were the Sonos Amp connected to by the way?.. I’m just trying to ascertain what you are using for your new simplified setup, or were you outputting the line-in TT audio to any other Sonos devices?

I just hooked this configuration up and sent it to a pair of One speakers, lots of clipping. Line Out was set to 10. Does not sound good.

It’s a set of Monitor Audio Silver 5i speakers. 8ohm, I believe. So should be fine?

The setup I’m looking to switch to is 1970s Turntable + Phono preamp + Amp (connected to Monitor Audio Silver 5i speakers) along with some One speakers.

In this article Sonos states it so simply:

If your turntable does not have a built-in phono preamp, you’ll need to place one between the turntable and Sonos player.

Okay, I got a preamp because my TT didn’t have one. So why does it sound horrible now? 😂

Go to Settings → System → PORT/AMP → Source Level and check the settings. They are probably different on PORT and AMP. Incorrect settings here can cause input overload. In my opinion the setting descriptions poorly worded. “Low” means “Low level” for the source. If you are having input overload, you need a higher setting.

Low impedance is a good characteristic for a line level output because it will be able to drive longer cables without issues. This does not imply that one could connect a pair of speakers to a line level output. A low impedance output for a line level might be 50 Ohms. In the overall line out universe this is very low and a great SONOS feature, but this does not imply that you can connect speakers. I have connected headphones to SONOS Line-Out. Amplifier outputs, on the other hand, can have an output impedance of 0.0x Ohms. In this respect AMP is also very low and this is good. There are other characteristics of AMP that make it appropriate to use with very difficult to drive speakers that will fluster lower quality amplifiers.