Speaker for Mcintosh MC 30

Go with a speaker rated at 90db or higher , this should work well with the Mac monos.

JBL 43xx series and 6L6 are big buddies since long. Plenty of restored units will humiliate B&W 805S. In fact that I really like B&W 805S in particular, the JBL43xx series will be better match. 
Floor stander I'd pick JBL L800 if you'll be able to find it.
My favorite pick on tubes is 6CA7 fat bottles.

Good advice above.  You could also look for a pair of original Klipsch Hereseys.  Good luck & happy listening!

You could find some Coincidents which are quite efficient.  However, with a vintage amp that really has great mids you might be really happy with a single driver speaker such as Lowthers.

I absolutely would not use EL34’s in an MC-30, unless it has been somehow modified to be compatible with them. The MC-30 was designed for the 1614 or 6L6-GC. The EL34 differs from those tubes in numerous ways, including not only electrical parameters but even the pin to which the suppressor grid is connected.  The pin-out difference could be resolved by adding a jumper between pins 1 and 8 on each of the power tube sockets.  But I would expect the differences in electrical parameters to result in degraded sonics at best, and a blown power transformer at worst, eventually if not sooner.

Good luck. Regards,
-- Al

Don't know your price range but there are some Zu Definition IVs on Audio Circle. Look them up on Hi Fi Shark. 101 db eff, Keith R takes really good care of his stuff and they are broken in. 
I've had a pair for three years and doubt I will ever audition another speaker.

Hi SRafi, I know it's allready some time gone since you opened this thread. Anyway, maybe my words get thru to you.
Long story short, I had a nice little system working in a decent room. Then moved to large appartement. No sound anymore. finally could buy a pair of Khorns...and it started to sound again in my new, very complex space. Never sounded the same like before. Then my 8W power amp got sick, and a friend lend me the mc-30s - suddenly the music started to play again. could find a pair for myself and started to look for best tubes. Finally ended up with the greatest sounding combo in my life...the mc-30 gave the lacking bass back to the Khorns...PreAmp was a Shindo Monbrison...I am convinced that the MC-30s are good compagnions to the Klipsch speakers...as both are native americans of a certain period.
hope u find a satisfying way to a great sounding system. cheers from the chocolate mountains...mark