Speaker for Mcintosh MC 30

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