So many brand options and different levels for affordable, I’ll not tread there.

What I will suggest is looking for a high efficiency speaker that sounds good to your ears.

Personally I’d go with Klipsch as I love the sound and the efficiency lets you crank the volume with no power issues.

https://www.klipsch.com/bookshelf-speakers

The Sonos Amp delivers more power that most HiFi stereo amps and will perform just as any HiFi amp will with the speakers of your choice; it will not be a limiting factor. There are many excellent standmounted speakers that deliver quality sound from makes like Dali/KEF/Q Acoustics to name just a few and the best way to decide is to listen to them playing music you like.

If you have access to the used market, that is another source of affordable kit, supplied by audiophiles that are always upgrading perfectly adequate kit with most of its service life still in it.

Only you know what sounds “best” (to you). People tend to have strong preferences. There are some highly regarded speakers that I would prefer not to accept as a gift and I have friends who don’t like speakers that I like. Regardless, we still get along.                                                            

I agree with others. However, you may get a few speaker recommendations based on price if you are willing to specify your budget limit.

Also know that even a good speaker can deliver poor results if you purchase cheap cables. So you might consider researching those as well.

Cables from a hardware store will work just as well as long as they have a copper core of adequate thickness for the length of cable needed, with a decent insulation sleeve; all they have to do is carry the current across. Equally important would be integrity of the termination at both ends, so some care is needed there.

I too at one time believed that OFC cables as you described were all that is needed (but not from a hardware store) . I also found that cables with a supposedly good insulation sleeve complete with cut away diagram of construction didn’t eliminate unwanted RF and other interference as well as advertised. In fact the cables I use today most ( at first glance) would think a waste of money until one does a A/B comparison at home. So IMO cables make a difference and not just any OFC cable. And yes…I agree well constructed termination ends are important as well.,

I might also add that well constructed phono cables and interconnects (if using and outboard pre-amp) make a difference if planning to use a Turntable with the Sonos Amp

Testing cables is harder than one expects. In my experience a major part of the improvement when installing brand new ‘tricky’ cables is due to the accidental cleaning of the contact surfaces while replacing the cables.

That said, sometimes there are differences. In a setting with multiple systems and multiple observers, we had a single ‘tricky’ interconnect cable and anyone could move that cable to a different system without notifying anyone. All of us had the same experience: When the cable was first installed in a system, the system perked up. At some point the cable would be moved, unannounced, to another system. We would all notice that the first system degraded a bit and another system would perk up. On investigation we’d notice that the ‘tricky’ cable had moved. It was not possible to see the cable without digging behind equipment.

Best place by far for objective reviews is ASR.

https://www.audiosciencereview.com/forum/index.php?pages/SpeakerTestData/

In 2021, I’d go with powered monitors vs passive, though.

Powered speakers are no fun for the audiophile because there are no speaker wire or amplifier purchases to fuss over.

Powered speakers, even when using the same speaker components and enclosure, usually sound better than a traditional external amplifier setup. This is because a better crossover scheme can be used and there are essentially no speaker wires.

So would I, but the OP seems to have a Sonos Amp already.

The budget end of studio monitors tend to be powered as opposed to active, with the 2 channel amp housed in the mains power connected master unit, with a speaker wire running from the master to the other unit in the pair. Since that market looks to function over form and will not spend on eye candy and brand appeal, much the same sound quality as Sonos can be obtained for about half the price, using something like an Echo Dot as a source for streaming.

Thanks all for your responses. I’ll have a chance to check out some speakers over Christmas break at a not quite local, but accommodating Hi Fi store. The Dali/KEF/Q Acoustics seem to come up well in reviews, but I want to stick to 8 ohms in case I feel like I would go to 4 speakers some time in future.

I will also listen to Klipsch and Mission. The seem to be rather polarising - lots of love and lots of  …..

I’ll also keep an eye on the cables, etc.

Thanks again and stay safe over the holiday period.

If you get a chance to listen to the original Klispch don’t pass it up. Do not buy a pair as your spouse will kill you (53x31x28 and 220 pounds)) but you really need to hear one hooked to a hefty amp to appreciate what so many speakers are missing on the low end, even setups that have a Sub included.

https://www.klipsch.com/products/klipschorn

My spouse tolerated my smaller (40x24x24 and 200 pounds) La Scalla pair for a lot of years, the cat loved crawling inside too.

https://www.klipsch.com/products/la-scala-al-5