Mechans' comment re: "tube output stage is critical, period" is probably fair enough, overall. In the case of the RS6, it's even more applicable. Speakers which have a spike in impedence in the presence range (IIRC, the RS6 qualifies - as does the Merlin VSM, another speaker that "flatters" tube output stages) sound more dynamic and alive with the right tubed ouput stage. You might get a taste with tubed drivers and SS output, but you won't get the whole deal.
Good Luck.
Marty
Good Luck.
Marty