Mbonn,
Like virtually all things audio, EL34 vs 6550 is a matter of tradeoffs and personal opinions.
Generally, the EL34 has better midrange, and the 6550 is more powerful and has better bass. Using lots of EL34's will give you plenty of power and bass, whereas using lots of 6550's will not give you better midrange. So if you're going to make a big, beefy amp, you might as well use plenty of EL34's and get the best of both worlds (or close to it).
At least, that's my opinion.
Duke
Like virtually all things audio, EL34 vs 6550 is a matter of tradeoffs and personal opinions.
Generally, the EL34 has better midrange, and the 6550 is more powerful and has better bass. Using lots of EL34's will give you plenty of power and bass, whereas using lots of 6550's will not give you better midrange. So if you're going to make a big, beefy amp, you might as well use plenty of EL34's and get the best of both worlds (or close to it).
At least, that's my opinion.
Duke