I have the Warner box. I am not saying that W.F. didn’t make studio rcordings, he made plenty of them, but most of the available recordings are either concerts or Radio Broadcasts. W.F. studio recordings are generally felt to be inferior as performances to his live concert recordings or Radio broadcasts. One of my favorite Furtwangler recordings is Bruckner Eight with the VPO from late 1944. I believe that there are at least two recordings from different days. One is the actual Radio Broadcast made with a very small audience, probably a few Nazi bigwigs, the day before the actual concert, which I believe was also recorded and subsequently both have found their way to CD. I have the one that is sans large audience and it is the most thrilling Bruckner 8 out there, and it really sounds good for that vintage. btw, the Furtwangler set to have is the DG SACD set, if you can find it.
Van Beinum--I haven’t listened to any of his recordings (except the odd bits that come on the radio) since the lp days. I believe the Eloquence Label put out a good collection recently