Flexible hose to rough in valve in tub

[sxotty]

I have a quick question. I got a roman tub faucet pretty inexpensively and it has the rough in valve with solder connections.

I have PEX supply lines and a drop ear elbow thing so I can connect it solidly.

Can/should I solder on threaded connections and then just use the flexible supply line to bring water from the pex to the rough in valve or do I need to solder it?

Valve is kind of like that one.
http://www.**************.com/Prod/Delta-R2707-Roman-Tub-Whirlpool-Faucet-Rough-In/23990/Cat/1089

Flexible lines would be way easier as I would not need to line every thing up perfectly, but I don't know how reliable they are.

[hj]

The are not designed for installation is concealed areas, especially since they are often sealed up forever. And they are also too small internally to give a good flow for a roman tub application.

[jadnashua]

Many, but not all, valves that have threaded male inputs will also allow a pipe to be soldered into it directly. Try a piece of pipe and see if it will fit inside. If it does, you can clean it and the pipe, flux, then solder in a stub, then connect to the pex with whichever transition fitting you want.