Authenticator and Decoder

For MQA type, what is the different between Authenticator and Decoder.
If I connect it using RCA cable from Amp to the Rose250 to do all the MQA decoding from Rs250, I use “Decoder”.

What if I use my digital coaxial cable connect from my amp to the Rose250. Do I use Authenticator ?

Hello,

MQA Authenticator only determines whether the sound source is MQA, and bypasses the sound source to the USB DAC as it is.
MQA Decoder delivers MQA-decoded sound source to USB DAC in case of MQA sound source.

If your external DAC supports MQA, I recommend using MQA Authenticator.

It doesn’t matter which one you use, so I’m giving you my subjective opinion.
If MQA is not supported, it is recommended to use MQA Decoder.

But I am using a digital Coax to connect from my McIntosh C52 preamp to the RS250.
My McIntosh doesn’t do MQA. If I am using digital coax, that means the RS250 won’t do any MQA decoding at all. It will not work if I choose MQA Decoder from the ROSE right ?

If I use MQA Authenticator , would RS250 do half of the unfold for me?