| For someone accustomed to and "needing" resistance, a free blowing horn can be more tiring. I need to use a mpc with a tighter backbore to get the resistance I need (desire) with a large bore horn. So, I think it depends on your total setup (player/mpc/horn) and what you're used to.
Speaking to impedance, there was a great article in the ITG Journal in the last year or two about impedance and it's impact on trumpet volume. Basically it said that higher impedance horns translate more of the energy they receive into sound, so that they're louder for a given effort. How you perceive this loudness from behind the horn is easy to misjudge.
Tom Moore, Phd. was the author, I believe. If you've take the journal it's a "must read."
Dave |