Between these options I'd go with the Soulution combo, but before you drop a bucket of cash on them I really think you should try the Audionet amps from Germany. They are designed as the Soulutions to be very low distortion, high speed, high damping factor (10000). The MAX monos are a much better deal at $26k/pair and sound just as good IMO, not to mention they're more powerful than the 501s.
What I don't like about Soulution is the ripoff prices they charge now for their products. In 2005, when the brand was unknown, a 710 cost was 18k Euros in Germany, with inflation it should be now about 21k Euros, but it goes for 37k Euros; 16k added just because it got good reviews and became an established high end brand. I hate it when a manufacturer does this. The US prices are worse still.