Wow... a few things--
-You did sparge, when you added the 2L post mash, so your post title is a bit odd/puzzling. If you did not add the 2L post mash, you would have achieved your no sparge brew!
-The Braumeister is indeed a no-sparge system as it comes out of the box. You can choose to sparge, but it is not necessary.
-Recirculation is not sparging, it is exactly as it states-- moving (recirculating) the wort/liquor that is already present-- that is it.
-When a brewer does a decoction mash, higher efficiency is generally achieved.
But, good on you. Are you doing a true lager Scharwzbier, or using an ale yeast? If Lager yeast, how are you managing fermentation temps?