I really don't thing a 300b based SET @ 8wpc is going to be enough power for the Devore's at 93db unless your listening at very low levels. I tried a 300b SET on some Living Voice speakers that were 94db and yes they sounded good but constrained if i was honest they really needed 20-30wpc to wake them up i'd assume the Dveores will be similar. Maybe a paralleled 300b SET at 16wpc, but your getting into big $ and big $ to re-tube down the road.
The Spark at 18wpc will probably be really nice though. looks like an interesting amp and Ayon gets great reviews never heard one though.