PHD, some Pass labs, First watt, Threshold ect, had very low input impedance <33kohm and low gain.
So yes they would be suited better with buffered passives or active preamps. Rather than just a passive attenuator.
The ones that have >33kohm (the standard being 47kohm or more) input impedance, and 1-2v input sensitivity for full output, would suit a passive attenuator.
Cheers George