The Silverline speakers are wonderful with tubes. I haven't heard the Coincident so I can't comment on them. You might also want to take a look at the Legacy Signature IIIs. Legacy's website is www.Legacy-Audio.com. I haven't heard them with a tube amp personally, but I've heard they sound very good and have a rated efficiency of 93dB. They are 4 Ohm though. They are about 12" X 12" X 50" and weigh in at 130 pounds. Good Luck!
Greg
Greg