Irdac 2 suddenly playing dsd 256

Hi all
I noticed something strange.
After selecting my arcam driver. It allowed me to play dsd 256.
This is unusual as it never allowed me to select 256.

I didn't realise it at the time but it was playing at dsd 256.

Thing is the irdac only allows 64 128.

Why would this play?
Driver also informs me 11289600hz.

Is it DOP?

i have no idea if its playing dop
iam using hqplayer has well as jriver/
i f select 256 in any of those players, it plays? looking at the irdac specs its 64 128.

i did notice that playing 256 sounded a little better, no idea why. driver info says playing at 11..... 256.
to use dop you would need to tell the driver to use it. which iam not

i noticed in hqplayer the cpu peaks at 20% with 256 where as 128 12%.

i have just set jriver to 4x native dac

and it players ok sound about 2 db lower than 128, jriver tells me no changes being made playing at 11.3.

confused...