220 ohms (balanced) into 10K ohms should be absolutely no problem. Why do you think it might be? Who recommended 1:100 ratio? Typical recommendation is 1:10, minimum. Also, are you taking into account the input impedance of the Bryston in balanced mode? Because it might be 20K ohms, not 10K. Bryston are not very forthcoming about stating the input impedance of their high level inputs, but after downloading the owners manual, I did see that the TAPE IN input, which is single-ended, has an impedance of 10K ohms. This suggests that the balanced inputs would be in fact 20K ohms.