actually, capacitance per say is not a problem, so long is it, along with the inductance (and resistance) of the coaxial cable, results in the correct impedance (75 ohms for AES/EBU). It is the impedance that matters, not the capacitance. Failing to match the impedance (which would happen if you cut the capacitance without a corresponding increase in the inductance) will result in poor performance. Get the impedance right and the only limiting factor will be losses in the dielectric and increasing resistance due to skin effect as the frequency goes up. Even cheap TV aerial coax has a performance vastly superior to plastic optical connects.