Yes they are. Two in my preamp and 4 in my CD player. Waiting for the larger values for my crossover. I also placed 8 in some Thor amps. They are spectacular. Several of us replaced Duelund CAST in our preamps and love the improvement. The Duelund caps are wonderful in our preamps, but these are better to our ears.
I suppose I don't know for sure if the speaker value Jupiters will be as good or better than the Duelund as I have only used them in electronics. Beta testers say the speaker value Jupiter caps are just as special in crossovers.