We're roughing in our new house right now. I'm planning to pre-wire for in ceiling speakers in the back porch and kitchen.

Plan is 2 speakers in each location. Both run off of a Sonos amp. Plan to run them through a volume control switch in the wall so as to be able to have different volumes on each pair of speakers.

Here's my question. How much distance do I need between the speaker wire and the romex? Reading online I've seen reponses from it doesn't matter to 12 inches minimum. Currently I'm planning to put the switch by the back door. There is already a light switch there. I'm planing for a separate box, but they'll be in the same stud space and its a smaller that normal stud space because of the door. At this point it's not hard to change the switch location. I just have to make the decision soon.

Looking for advice to 1. be safe and 2. not have any interference on the speakers.

You could run shielded speaker wire, however the light circuit is not high amperage so it's unlikely to induce any interference. We installed speakers for a Sonos in a doctors office with the speakers near florescent lights and didn't have a problem.

PM Cast.

Hancock nailed it. Use good speaker wire and you’ll be fine. I used round Monster speaker wire rated for in-wall installation in my walls here. Cheap speaker wire would be fine too, but won’t last like the good stuff. My wire is 25 years in the wall and working great.

This is the wire that I bought. I can return it if I need to use something different. I bought 14/2.

https://www.amazon.com/gp/product/B01N5LC545/ref=ppx_yo_dt_b_asin_title_o01_s01?ie=UTF8&psc=1

That wire looks like the wire I used. Just be careful when you staple it to the studs. I would use a staple gun that shoots round top staples that is made for this purpose. And no worries about spacing from the romex.

I’m an A/V systems designer, I work primarily in the commercial space, but the physics are the same no matter where you evacuate them. The wiring between the amp and the speaker is the least sensitive segment of the signal chain in regards to interference, And have a very high signal to noise ratio especially in the relatively short distances involved in most residential construction.

To both 1 and 2 you are fine in the same bay. In theory keeping them spaced is better, to reduce any inductive interference, but In practice This not much of a real world issue for speaker level signals, and residential power and in a normal home setting you will not hear the difference, but might see it on an oscilloscope and probably explains the verity of conflicting info you have seen online. I’d avoid running the cable Speaker adjacent and parallel to the 120 For any real length, And probably come up the opposite side of the bay as the Romex and avoid close proximity to fluorescent Transformers just to be safe but don’t kill yourself, or worry to much, you will not hear the difference.

The cable you linked is CCA, Copper clad aluminum, you are better off with straight copper, it will age better, and be more stable in an outdoor environment like a porch my go to is Belden 6100ue https://catalog.belden.com/index.cfm?event=pd&p=PF_6100UE

That’s a hell of a first post from a three year lurker

Where's he been, in jail?

the more wire you run the more resistance you have ... the more power you 'll need for cleaner sound

In hi fidelity

you want as short a cable as possible
thick cable if you're driving bass

In your case , you're just running ceiling speakers
probably not too worried about hi-fidelity
Use 12g, good copper with some kind of attic/heat
resistant cable shield

I used to build custom high end Loudspeakers
I designed my own crossovers using software
to model different drivers using their Es, Fs etc ..
and have test equipments to measure
Frequency Response.

I can say that 2 things stood out

Good drivers (midrange and tweeters)
and good amps (high voltage , high damping factor )
make the most improvements.

The enclosure is also important, I can hear
muddy bass if it's flimsy. (and I built my own
custom enclosures, down to exotic veneers
and wet sanding final finish )

Ceiling mount speakers are not hi fidelity
but do make sure they have solid mounts

I can switch between a $2000 exotic cable
and a $200 solid copper cable.... and I can't
say that I can tell an $1800 difference in sound quality
(meaning; don't waste your money on cables, your
ears probably can't hear it )