I purchased an American Standard "Cadet" tub faucet/showerhead kit from Home Depot. The mixing valve has threaded female ports. Do I just screw in a threaded male copper adapter (with Teflon tape on the threads of course), then solder pipe to the adapter? It seems awkward to have threaded ports on the mixing valve because a) once you solder the pipes in place, you can't tighten that connection anymore anyway; b) it seems risky to have a non-soldered connection here, since it will be enclosed in wall/tile and I won't have an access path if it leaks in the future (I have back-to-back bathrooms). Or can I put solder in the threads?