You can run the Koss ESP-950 right off an SRM-T1, no problem. No need to change the bias. I do it all the time. You just have to have the right connector on the Koss / or an adaptor.
You can also drive Stax "pro" bias headphones right off the Koss amp, even though the bias on the Koss is a bit higher. Again, what's needed of course is an adaptor for the headphone plug.