I've owned a C9 for many years. I have had the chance to compare it side by side to some luthier instruments in the $3000-6000k range and to my shock and dismay I often preferred the C9. This is how I discovered that price, maker, etc. can be highly subjective in the classical guitar market.
I've also compared it to a C12, and honestly prefer the C9/C10. The C12 has lattice bracing, which allows it to be driven a bit harder to get a little more volume, but the C9 has a more beautiful, alluring tone. The C12 sounded sterile and boring to my ears. The small bump in dynamic range you get from the C12 IMO is not worth the loss of tonal beauty. The C12 is quite overpriced and not an upgrade over the C9 if you ask me. I too prefer the C9 over the cordoba espana series guitars.
At the price of the C12, I'd take a look at a Yamaha GC32. The GC32 is a bit more lively, balanced, responsive, clear with a higher dynamic range, while also having a beautiful tone, albeit quite different from the C9. The C9 has a warmer more "spanish" tonal profile while the GC32 will be less forgiving and require better tone/technique from the player.
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