@charles1dad Exactly! The 6EM7 has two different triodes inside, one has high gain and low Gm so is used aptly as a voltage amp where its only job is to make the input signal larger, which is then cap-coupled to the higher Gm, lower gain and lower output impedance section of the tube. Then that is coupled to the 300Bs grid by a 2:1 interstage transformer so it makes a dog's lunch out of the 300Bs grid current and allows the amplifier to realize the full power of the 300B. My 300B is similar, but takes a slightly different road to get there (same principle however).
Regarding speakers, another trick is to use an output transformer with a higher primary impedance to drive a lower impedance speaker. I've built amplifiers for several customers where their speaker's impedance profile dipped down heavily into 2 ohms, and the SET was able to drive them just fine, or more so surprisingly fine!
All the best, Aric