N, welcome. As Fred points out, the spec for low end extension measured anechoically isn't similar. The EP350 shows a 28Hz number on a +/- 3dB standard, while the EP500 shows 18Hz at a tighter +/- 1.5dB range. If these measurements were taken using the same procedures, it indicates an advantage for the EP500 of at least 10Hz.

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Enjoy the music, not the equipment.