The amp is not that powerful for low impedance stuff at all. The amp is class A but specializes with voltage rather than current. That's why low impedance stuff does not do well on it, namely the K701 and K702. Both models crave current but the Phonitor/Auditor lack a high current output. Not only that but both amps have a 9Ohm output impedance which means the headphones should be around 70-80 Ohms at least. Grado's sound fine on the amp because they do not need much current as they are highly sensitive.
As for the cables, BJC are nice cables. I've owned cables from them in the past and they were built really solid!
It seems counter intuitive, but I'm not up to speed on Ohms law, ha ha.. Many thanks.