I suppose if you're thinking of potentially upgrading to a 5.1 setup at a later date it could be limiting, since getting analog 5.1 out of anything other than a PC these days is probably quite rare.
● If you build up a Sonos 5.1 setup piecemeal, you're paying:
- Beam: €450
- 2x One SL €400
- Sonos Sub: €800
That is a lot of money for what you end up with, and you'll get audio lag since the surrounds and subwoofer are wireless - not great for gaming.
I would certainly recommend a passive 5.1 setup in place of that, since you can choose the components you want and don't have to spend nearly as much.
● Passive speakers can be more flexible if you want to upgrade from 2.0 to 5.1 later, but may have a higher up-front cost if you don't already have an amplifier.
- Do you buy a smaller and less expensive stereo amplifier now, or do you buy a bigger and more expensive HDMI 2.1 AVR?
- Will matching speakers still be available by the time you want to upgrade?
I've known a lot of people that buy a passive stereo setup thinking they want to upgrade it to 5.1, but end up buying a whole new set of speakers when that time eventually comes a year or two later - often because it was cheaper to get a kit than buying individually.
Depending on the speakers you're looking at though, an AVR with a pair of passive speakers could end up in the same price range as the Sonos Beam to start with, and should cost far less to upgrade to 5.1; e.g. €250 AVR and a pair of €100 speakers, then three more €100 speakers and a subwoofer.
You do also have the option of being able to make your current stereo speakers the rear surrounds, if you feel that you want to upgrade them when you go 5.1 rather than adding more of the same speaker. €1650 can go a long way.
● To put it in perspective: if you look for deals, you can probably get a pair of JBL 305p for close to the price of a
single Sonos One SL.
The reason that I like active monitors is because they are flexible; since there's no need to hook them up to an amplifier.
If I had a pair of active monitors in my living room and wanted to upgrade that to an all-new 5.1 setup, the monitors can be repurposed anywhere there's a power outlet; e.g. in a bedroom. A €40 AirPort Express v2 off eBay and a €10 cable later, and those monitors are now an AirPlay 2 zone. Or you could use a Chromecast/Bluetooth receiver if that's what you prefer.
That still leaves you with €1350 or so to spend on a 5.1 setup, compared to the Sonos Beam, One SL, and Sub.
Of course that doesn't get you into the Sonos ecosystem, where everything costs 10x as much and you have to buy the Sonos Port at €450.
If you're locked into Sonos already for multi-room audio, it probably is cheaper to buy their own speakers so long as you are happy with how they sound.
Active speakers are certainly not ideal for every setup, and as I've said before, they are "dumb" devices in the age of smart speakers. But that also means your money goes a lot further as far as sound quality is concerned.
At the same time, if you already have an amplifier, or are getting one anyway, you're paying for an amplifier inside every active speaker - so in theory your money goes even further with passive speakers. In practice though, I don't find that to be true until you start looking at higher-priced speakers. There are a lot of passives in that price range which aren't very good at all.
