Marcinkiewicz E9M. Klein vs Yamaha TR-17D4
The Marcinkiewicz E9M. Klein has a wider cup diameter, the Marcinkiewicz E9M. Klein has a larger throat opening.
Cup Diameter
The Marcinkiewicz E9M. Klein has a cup diameter of 17.32 mm / 0.6819 in compared to 17.30 mm / 0.6811 in on the Yamaha TR-17D4 — a difference of 0.02 mm / 0.0008 in. A wider cup generally produces a fuller, darker tone but requires more air support.
Cup Depth
Both mouthpieces share a deep cup depth, so the sound character from depth alone will be very similar.
Throat Diameter
The Marcinkiewicz E9M. Klein has a wider throat (3.66 mm / 0.1441 in vs 3.65 mm / 0.1437 in). A wider throat allows more air through, increasing volume and projection but reducing resistance.
Which is better?
Neither mouthpiece clearly dominates the other — the right choice depends on your embouchure, playing style, and the sound you're after. Try both if possible.