German Brewing

I bought some Spalt pellets hops and the AA is 2.4%. I will need a lot to get to 25 - 30 IBU for my next Pilsner. Should I use German Magnum ( 13.2% AA ) for my 60 min addition, or just use a lot of low AA Spalt? I plan on using 30 and 10 and 0 min additions of Spalt anyway.

It all depends on what you are going for. Many Bavarian brewers use all low AA hops for beer. Many other German brewers do the high alpha bittering low alpha aroma/flavor.

I am not sure what I am going for. My usual Hallertauer I buy in bulk is gone. The AA was 9%. Now the best I can do is around 3.6%. I have to use a lot to get to the same level of bittering. Will using a lot more hops at 60 min affect the flavour?

It could get vegetal on you. Normally you want to pick a beer and replicate it. Picking a style and using generalities is quite difficult.

Look at the beta's. For Helles and Pilsner, if the beta is high, then it's worth it to me to go with the low alpha. If not, then use the magnum.

The brew shop where I bought these said the beta is 3.5% - 5.5%.