You wouldn’t need to go through an external mixer unless you wanted to add extra channels/mics (Yamaha MG06 is worth a look if you do) as the SX has XLR outputs, as you say. You can go straight from the SX to the speakers.
(By the way, have a search on the forum for budget speakers, it’s been covered a couple of times recently with all the background info you will need. (Don’t buy Behringer speakers – there are good, budget, alternatives). Of course, if you have specific questions then feel free to ask 🙂 )
Pretty much all XLR cable says Microphone Cable on it – this is to differentiate itself from DMX cable, which is used for lighting control and has different internals, although it may look the same from the outside and also uses 3 (Or sometimes 5) pin XLR connectors, as well as to differentiate it from Speaker cable, which is used to go from Power Amps to Passive Speakers and is generally 2 or 4 pole rather than 3, and normally has either Speakon or TS Jack connectors on the end..
I use the “No Bull” XLR cables from Amazon.co.uk – they are really well made, the connectors (whilst not being Neutrik, which are the brand leader for Pro Audio/Power connectors), are strong, all metal and have worked fine now for a year – the lifetime of the cable, being used once or twice a week every week. I own 4 x 6m cables for my speakers (2 x 6m for each so I can daisy chain or not have miles of cable for each) and 1 x 2m for my handheld mic – which I use from just above the mixer.) I fully recommend them if you are in the UK. They also come with their own velcro cable ties and, best of all, are brilliant value. And you get a choice of colour!
I would (and I do, but from a mixer) wire from the XLR outputs Left channel going into the speaker on my left, and the Right channel going to the speaker on my right. I rig this the other way round (Left and Right swap) if I am doing PA work however.. But that’s different..
bob6397