Can I add a DAC to new Sonos Amp?

It looks like there are a few misconceptions here.

The Amp accepts an analog Line-In. Internally Sonos digitises this at 44.1kHz sampling rate. This is able to encode audio frequencies up to 22.05kHz, i.e. beyond the range of human hearing.

So:

• no, you don’t get a maximum of 96kHz, whether as a sampling rate or a frequency response
• an external iFi DAC on the iMac may well do better quality-wise than the iMac’s headphone outlet in terms of decoding to analog, but this is then digitised at 44.1kHz by the Amp on input as noted above
• as a human this is all you require

Sorry I meant sampling rate of 96khz - im sure i read somewhere that the amp can accept 96khz through its line in? or it may have been a dream..

A pity the iMac doesn’t possess a HDMI arc output.. sigh.

Since the Line-In is analog, it can not accept anything digital at all, regardless of sample rate.  

But it wouldn’t be digital would it if the 3rd party dac has already converted it to analogue ?

As I say, the analog (not digital) Line-In has an effective frequency response up to 22.05klHz, as it is then sampled at 44.1kHz. This is higher than human hearing can go.

Why on earth would anyone be interested in the Amp accepting 96kHz, when only animals such as cats, mice and bats are able to hear it? 

Wow.. I was expecting a response with a cat mouse or a bat but not within the 1st hr...

And rats? Someone may have a requirement for a multi zone ultra sonic rodent repellent that could also be used to play music. 

It also wouldn’t be “higher than 96 kHz” which is what the original question was asking.  

On a side note, if you play so-called “high resolution” audio through the Sonos Line-in, it will sound exactly the same at 96 kHz as it does at 44.1 kHz, as every properly conducted double blind test has shown.  You simply aren’t going to hear anything above a sampling rate of 40 kHz (far less if you are not a teenager).  However, this begs to ask why you wouldn’t bypass all the extra processing by simply down-sampling the “high resolution” audio to strip out the snake oil in the first place? 

And then it appeared, just like that…  snake oil...

Do you have actual objective proof it’s not, or are you just here to lob bombs?  If the latter, I’ll bow out.   I’d rather not deal with the audio equivalent of flat earthers.