In the topmost circuit we see the approach of using two gain stages with one complete RIAA equalization network in between. One 6922 or 12AX7 or 6N1P per channel is all that is needed. If grounded-cathode amplifiers are used, a plate resistor and a bypassed cathode resistor, are all that is missing. Refinements might include eliminating the cathode resistors altogether by using batteries to bias the triodes. Further refinements might entail using a truly high-voltage power supply, say a 1000-volt B+ with a staggered turn-on; or maybe using a truly low high-voltage power supply, say 100 volts with solid-state constant current source loading of the triodes. Somewhat paradoxically, both of these approaches yield the same results: high gain and good power supply noise rejection.
Alternatively, the generic grounded-cathode amplifier topology can be retained, but the number of triodes in parallel can be increased to 2 or 4 or even 6 or 8. The following schematic illustrates this approach. The circuit is as straightforward as can be imagined, the only twist being the many triodes (four in the first stage and two in the last) used in parallel.