The takeaway is that is impossible to "overdrive" the 300B. By contrast, a charmer like an EL84 can be driven with a whisper ... even a 12AX7 biased at 1 mA will sound good as a driver (which doesn’t work with any other power tube). A classic Mullard circuit is ideal for a pair of EL84’s since they are so easy to drive. 6L6's take a bit more muscle, so 6SN7's are a better choice.
The 300B is the opposite. A high voltage, high current, and ultra low distortion driver is mandatory, otherwise you never hear the 300B.
A simple and very effective way to drive 300bs is to use a cathode follower driver, direct-coupled to the grid of the 300b as it fulfills the requirements listed above. This requires a B- supply but you can control the grid so well that it can be driven class A2 (grid current) and you can easily overdrive the tube using a single 6SN7 section. This also allows for a much smaller coupling capacitor; 0.1uf (at the grid of the 6SN7) will allow -3dB bandwidth at 2Hz. This frees up the Voltage amplifier/driver of conventional design from a highly capacitive load. The downside might be that the power tube has to have its bias set correctly (so a provision to measure current is needed), which is done by setting the bias of the 6SN7.
Doing this I've been able to overdrive 300bs (even multiples!) quite easily. The CF circuit, without the typically large coupling cap that often gives CF circuits a bad rep, has a tight grip on the grid of the 300b; so much so that driving class A2 with the substantial grid current that tube needs is no problem. You can easily drive the grid +15V WRT to the cathode with good linearity.
The cost of a B- power supply is insubstantial when compared to the cost of a good inter-stage transformer and you get less distortion with greater bandwidth. You also don't have to introduce a power tetrode or pentode into the circuit.
A nice feature of this approach is the bias setting is very stable so might only need checking once or twice a year.