Connect 4 Speakers (varying OHMs) to One Amp

  • 26 November 2018
  • 8 replies

Userlevel 2
Hello Sonos Community,

I am doing a big bathroom renovation, and want to put 2 speakers in my "steam shower" and 2 speakers in the main part of the bathroom, for a total of 4 speakers.... all connected as one zone to one amp.

I have seen the documentation here that this is possible:

But, nothing is ever easy. :)

Since it's a steam shower, the speaker is going to get soaked. As such, I'm looking at marine-grade speakers.

After talking with Crutchfield, they recommended the "Kicker KM604W" speakers for inside the shower and the Polk Audio RC60i (or 80i) for the main part of the bathroom.

The issue, however, is that the Kicker marine speakers are:
4 ohm

The Polk speakers are:
8 ohm

On the Sonos link above it says:
To attach 4 speakers to a single Amp or Connect:Amp, the speaker impedance must be 8 ohms. Anything outside of that may damage the Amp, Connect:Amp, or speakers.

Yikes.... now I'm stuck!

I cannot seem to find any marine grade speakers that are 8 ohm.

I read online (after much research) that there are "Impedance matching speaker selector switch".
I cannot seem to make sense of that, so I don't know if it solves the problem or not.

Any insight is greatly appreciated in a big way.


Best answer by Chris 26 November 2018, 17:00

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8 replies

Userlevel 7
Badge +22
You can only connect the 2 4ohm speakers.

You can get an impedence matching switch to connect them all. It will make the load going back to amp a consistent 2 channel ohms it can handle.

Userlevel 2
Thanks for the super fast reply, Chris! Much appreciated.

Just want to ensure I'm following you here... apologies for being a bit unfamiliar with all this.

Basically, it sounds like I buy:
- Paid of 4 ohm marine grade speakers
- Pair of 8 ohm Polk speakers
- OSD Audio ISS4 4-Channel High Power Stereo Speaker Selector Switch with Impedance Matching Protection (using the link you sent to Amazon)
- Connect Amp

Then, I plug all 4 speakers into the "OSD Audtio ISS4" selector... and connect that selector to the Sonos connect amp.

If I do that, all 4 speakers will work...and the amp won't explode?

Will I take a heavy hit on quality... like, the volume will be super low on the speakers... or you think I'll be OK?

Thanks again! I did hours of reading online and you just gave me the answer in minutes, hehe.
Userlevel 7
Badge +22
Quality should t really suffer in my experience
Userlevel 2
Awesome.... thanks Chris..... you're my hero, as I knew someone would have the answer to this problem that had me totally stumped.

Did my shopping list in the previous post and general setup sound correct?

If you give it the thumbs-up, I'll start buying everything.... and be confident the amp won't explode.

Thanks again.
Userlevel 7
Badge +22
Your good to go
Userlevel 7
Badge +22
I used to have a 6 zone switch powwered by a single 90 watt amp and all sounded great.

I would get the Sonos amp though not the older connect:amp. More power plus future proof.
Userlevel 2
Awesome! Thanks so much, Chris.
I bought the Connect:Amp on Black Friday, so I'll try to give that a whirl first....

Really appreciate your solved the mystery for me!
Userlevel 7
Badge +22
They are a good deal on Connect amps right now.