Utilize Apple airplay with Apple Airport Express $99 (connect to preamp) and Apple Remote app free (iPhone).
Control your cumputers iTunes from iPhone with app and select your airplay speaker(s), in this case your airport express. (Your iPhone can also independently select this an airplay source for streaming if you wish.)
Then later add another wifi speaker with airplay or another airport express with an integrated amp/speakers in other rooms and control it all with your iPhone Remote app.
Works for me.
Control your cumputers iTunes from iPhone with app and select your airplay speaker(s), in this case your airport express. (Your iPhone can also independently select this an airplay source for streaming if you wish.)
Then later add another wifi speaker with airplay or another airport express with an integrated amp/speakers in other rooms and control it all with your iPhone Remote app.
Works for me.