Sonos AMP perfect level source technics/OMRED calcul HELP

​@craigski is correct.  The generally accepted method is to increase gain until distortion is heard, then back it off until the distortion disappears. 

Here’s another way to decide line-level...

In a quit room I set the line-level to high and listen for “hum” with the stylus in rest position. I lower the line-level until the “hum” is basically so slight that it can barely be heard. I can’t tell you what my line-level sweet spot is as I’m out of town. I can tell you the following;

• Pro-Ject Debut Carbon Turntable in Black (Sonos Edition)
• Pro-Ject Aluminium sub-platter for Debut turntables

• Pro-Ject Power Box S3

• Ortofon Blue Cartridge

• Sonos Amp

• Sonos Sub-Mnni 

• Cambridge ALVA DUO Moving Coil & Moving Magnet Phono Preamp
• Definitive D7 Book Shelf Speakers

I think you are over thinking the set up just adjust you level as needed for what you are listing to. all music is recorded and remastered at different levels and you will go crazy trying to chase levels. just enjoy your music and adjust accordingly. no hum your ok !

When we add a turntable to Sonos, especially a good quality TT and preamp, we have to accept that there will be a compromise in the audio we hear. Sonos is not totally analogue and since there is a good amount of audio processing going on, there are times where you will just need to trust your ears to get the best sound possible from your speakers.

As others have said, don’t overthink it. Adjust the levels where they sound good without distortion. It may be a little quieter than a traditional amp, but it is what we have for now.

This is a hot topic as of late, so if Sonos is paying attention to the many users who are adding analogue turntables to their systems, hopefully they will be able to rework the firmware so a turntable can have its own setting? Maybe a device that cost less than the Port to plug a turntable directly into?

Yes I know there are wireless options, but you can’t beat a wired sound.