I have sold many of them, and they work and work. The TX will plug into a 15A outlet (regular household outlet) but the SX has a bigger pump and needs a 20A dedicated outlet.
I love the SX when people ask me for a good solid value for a nice basic tub - it doesn't have a ton of jets, but it does have the Moto Massage jet, which I happen to love, and it covers your whole back for the 'price' of one jet.
HTH