Tom, raisins are grapes, and grapes add a vinuos quality to wine that no other fruit matches. But raisins can affect the flavor, although that is largely a function of which lind of raisin you use.
For peach wine, you would obviously want to use a white or golden raisin. These are usually made from Thompson Seedless Grapes, which are fairly neutral in flavor. You could also just use crushed fresh Thompsons in the wine. If you can find them, try Sultanas, the raisins of muscat grapes. They offer a nice flavor enhancement to peach.
Finally, you can try adding a white grape concentrate.
For raisins, use anywhere from one-half to one pound per gallon of wine -- the lower number is sufficient for body improvement. For grapes, use no more than two pounds per gallon. For grape concentrate, use 11 ounces per gallon.
Jack Keller, The WInemaking Home Page
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