1/8 max seems still too high to me. For example it would be satisfied by a 12.5 Ohm Zout amp with a 100 Ohm headphone, but that wouldn't be ideal in case of lon

1/8 max seems still too high to me. For example it would be satisfied by a 12.5 Ohm Zout amp with a 100 Ohm headphone, but that wouldn't be ideal in case of long cables. I'd aim to much lower impedance anyway, especially today that it's easy to obtain with common parts.