Question

What is the Connect line-in signal path?

  • 23 February 2019
  • 6 replies
  • 583 views

I’m trying to find out what the Connect line-in signal path is. For example, if a CD player is connected via the line-in input, does the signal remain in the analog stage or is it it routed through the Connect’s internal DAC? Sated another way, is the analog signal that exits from the line-out output the same analog signal delivered to the line-in input? Second, in what way do the Connect/Sonos App volume, tone and balance controls control the analog signal? Is the analog signal routed through the DAC?

Thanks, John

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6 replies

The analog signal is digitised on input. All controls take place in the digital domain. Output is via the DAC if it's to the analog outs, otherwise digital through the S/PDIF outs or as packetised data to other players in the system.
Thank you. I tried the pass-through option and it sounded quite a bit different—better, very similar to the direct connection to the amp. Is the pass-through option also routed through the digital domain? I’m trying to route an SACD player through the Connect for convenience sake. My amplifier doesn’t have remotely selectable inputs.
The 'pass-through' option doesn't affect the signal path. It's to allow the Sonos controller app to directly manipulate a compatible follow-on amp/receiver.

Perhaps you'd rather use the 'fixed' option. This sets the output to full scale, though the incoming analog signal is still digitised and the Line-In Source Level setting will affect the input sensitivity. Obviously the volume then needs to be controlled independently in the downstream equipment.
Is the signal path also unaffected in fixed mode? In fixed mode neither the volume nor the tone controls are available—they are disabled, shaded gray. In pass through mode the controls aren’t shaded gray but the have no effect. Fixed mode sounds the same as the pass through mode. In either case I can control the volume with the amplifier remote control.
'Pass-through' can be a bit confusing. The Sonos controls are apparently active but seem to have no effect, because they'd only be acting on a compatible downstream amp if one was present.

'Fixed' will send the signal out 'as is' without controls (volume, balance, EQ) -- which may yield effectively the same results as 'pass-through'.

However, as I say, the analog is digitised to 16/44.1 on input, and hence the dynamic range would be affected by the Line-In Source Level sensitivity. Also the analog out is subject to the quality of the internal DAC.

There really isn't an analog straight-through as such. If quality is a key consideration I'd suggest you route the SACD to your amp. Assuming you have a tape loop on the amp you could then send the signal via REC OUT into the Connect, and play from Connect through TAPE IN.
Ok. Thank you for your replies. That gives me the info I was looking for.