No, a line in on the newer Port is the same as the line in on the device it replaced, the CONNECT. 

Thank you. If there is no discernible difference in audio quality then I will not spend the $$$ on a new Port. Maybe new speakers instead :) 

I would buy the Port:

#1 - the Port is Airplay compatible and much more future proof

#2 - its not a lot more then a new Connect

#3 - I wouldn’t buy a used connect as it would most likely not be S2 compatible (no way of knowing ahead of time)

Search this community for a couple of threads that suggest that older Connects may sound better than Port in some cases, before going for a new Port. 

So you mind sharing where anyone would say there is difference that should factor in his decision?

The OP stated he will use the Port to stream to other Sonos devices.  The Line-In ADC and subsequent streaming to other devices bypasses the volume setting on the Port, so the not-yet-proven-to-actually-be-audible changes to the Port’s digital output when set to Variable volume mean nothing to the OP.  

I thought a Sonos spokesman stated (as quoted in a recent article) that there was a difference when using fixed vs variable on the port.  Based on some limiting factor when using variable volume.  But using fixed, it is bit to bit -- no issues.  Variable there is some control that kicks in above a certain volume level.  

Not a Sonos spokesman, a Sonos user (granted one with years of experience).  However, @ratty tested the actual output, not the audio heard.  All of the differences heard between the Connect and Port in variable volume mode could very well be slight volume differences.  As little as 1 dB difference, which won’t even be consciously recognized, have been shown to throw off a DBT.  So without a level-matched DBT, the jury is still out on whether the difference is actually audible. 

The article in question said:

The difference between the new Port’s audio quality and that of the older Connect, a Sonos spokesperson tells me, is related to the manner in which the DSP (digital signal processor) in each unit handles their analog and bitstream outputs. The DSP, according to this source, is designed to adjust for “the different characteristics iof] different recorded content… that impact volume output. The DSP helps to keep it balanced so that it protects the listener’s equipment and ears.”

It would appear that the processing (dynamic range limiting) is more aggressive in the Port, when using digital output in Variable volume mode.

The DSP isn’t involved when using digital out with Fixed volume.

It’s assumed, though not confirmed, that the dynamic range limiting is also not used on the analog outs, as there’s no danger of hard clipping.

Thanks @ratty.  Either I missed that, or read it and forgot.