When's the sansui from? Those vintage receivers tend to have headphone outs tapped directly from the speaker outs, just with resistors in the path. Therefore, I'd recommend a headphone that don't get affected by the high output resistance, assumming the sansui is from the 70's/ earlier 80's. Go for the planar magnetic tech as they won't get affected from the high output impedance, use the headphone out and later on perhaps go directly from the speaker taps with a custom cable if you feel/suspect the headphone lacks power.
Look into the t50rp mods like mad dog or the hifiman models. Do yourself a favor and spend that extra bit. For entry planar magnetics there's the mad dog (300$) and HE-400 (400$). Else, there's also other models, yet they are more power hungry and might require you to either get a dedicated headphone amp or go directly from the speaker taps of your receiver (which isn't bad at all, just more demanding and expensive).