I have always baked pound cake with regular flour, however I bought the cake bible and there is pound cake recipe that calls for cake flour. Can someone please tell me which flour is best for pound cake

I use AP flour for pound cake. I've never had a problem with it in the past and have never really seen a pound cake recipe using cake flour. Cake flour usually makes a lighter cake and I think pound cake, overall, is dense enough that you wouldn't really need to use cake flour, however, of you want to try it (economically) you can remove 2 Tblsp of AP flour every cup and replace it with corn starch. You will need to sift the flour an corn starch 2 to 3 times to get it well blended.

Pound cake is one of those rare types of cake where yo can actually use either - as long as you WANT the dome top that's typical on a loaf pound cake.

Some of the reasons why regular cakes dome are:
flour is too strong, meaning the flour has too much protein. All Purpose flour has more protein than cake flour.

Beating too long. One of the reasons youbeat pound cake a good long time is to produce a very fine crumb, and to slightly develop the gluten to support the structure.

(You'll also note that pound cake recipes typically don't have a lot of leavening for the amount of flour in the recipe.

Sooooo, when you WANT a dome like the typical loaf pound cake, then use AP Flour and beat a long time.

If you're baking pound cake that will wind up as a layer cake, then use cake flour, and beat a long time to produce that fine crumb. Cake flour is so low in protein that there's just not much gluten to develop.

Clear as mud?

My favorite pound cake recipe is Elvis Presley's Favorite which uses cake flour. I enjoy this recipe because the resulting cake will have a more delicate crumb than using AP.

However, whether you use AP or cake flour, be sure to use a bleached AP (all cake flour is bleached) as this makes a HUGE difference in the baked layers.

Unbleached flour and tons of butter will result in a cake that is slightly greasy toward the bottom of the layer... Bleached and cake flour will better support the butter in suspension (because of its irregular shape).

Rose Levy Beranbaum explains it so much better:

http://tinyurl.com/ye7on2l

HTH