Of course you can use wireless without extra adapter, but for conventional hot shoe you need a second one ooooor an adapter.
Good to see other choices.
The point of the Phottix is pass through TTL to the hot-shoe speed-light, and the receivers also accept Sony flash on top. Otherwise you are into a more complex set-up with more parts and some way to attach the transmitter to the camera when the hot shoe occupied by a TTL speed-light.
The classic simple set-up for portraits is one large source key directional light off-camera left or right, and an on-camera speed-light set to TTL for fill (using the Sony compensation controls to adjust amount of fill). A third Sony speed-light can be employed as a background, hair, or kicker light if desired.
I don't use this sort of thing very often, but if you don't have a battery driven studio strobe system, it works pretty well ... as long as you don't try to overpower the sun on bright days, or light a really large area or large group of people.
For a three piece radio kit @ $150. it solves a lot of issues. Reports I researched seem to indicate robust operation under demanding conditions like a wedding.
=Marc