I can't find any information in the manuals.
But this is IMHO not so tragic, because adding a PCIe card does not change power consumption that much, you should anyway calculate with a little reserve.
Check the power calculators that you can find from Enermax to get a feeling for, what components consume and which of them most like e.g. (CPU, GPU, ..) https://enermax.outervision.com/
I am not sure whether the Wikipedia entry is correct, it says that a usual PCIe slot (like with PCI) is able to deliver 25W. Well, calculate 25W and you will have enough headroom... According to this calculator a high end sound card uses only 8W ...
Compared to the usual 550-850W that I would estimate for a desktop PC with "normal" gaming equipment these 8-25W are not so severe (covered well enough).
X10SRi-F, E5-1650v4, Win10Pro20H2, Cub11Pro, UFX+ (v0.9734), XTC, 12Mic, ADI-2 Pro FS R BE