Black gate types C & Std etc

I want to stick some better caps in my phono pre amp (Electrocompaniet ECP1).
There are several 10mfd lytics in there and I want to upgrade these to black gates. Question is, which...
I do not want to pay stupid money so my options are between Std, PK and C.
I assume they are power supply decoupling caps but may well be wrong as there is only a few volts across them (2, 4 and 6) yet the unit runs of +/- 16 V supplies.

Would the safe bet be to just use C types designed for coupling circuits? Assuming that coupling may be more critical of cap properties then psu decoupling and irrespective of the exact cap role in the cct it will be better then the standard Elna in place?

Any thoughts welcome