Your transformers have a quite high turns ratio, so it would add a lot of gain to the circuit. With strong signals, you might get clipping even with the pad on. (But you can increase the attenuation of the pad by using a lower value for R157)
Anyways, the transformer should go after the pad, instead of C164 and C144 (but maybe check that the voltage across C151 (between the differential inputs of the amplifier) is very small, or else you might have excessive DC current going through the transformer windings, in which case you want to keep C164 and C144 and put the transformer right before those.)
If, once the transformer is installed, you have a bump boosting your low-end, you will need to increase the value of C5 and C17. With the extra inductance from the transformer, C197 and C202 might cut some highs out, so you want to watch for that too.
