The base cable that Townshend use is Goertz/Electrofluidics which has high capacitance/low inductance. Townshend, however, add a "network" to their cable which improves stability (I presume acts as or is an inductor). Isolda should be fine with newer Naim amps which I believe have less of a requirement for added inductance and I guess should be ok with older Naim amps which would become unstable when used with low inductance cables.
Regards,
Jim