Oh, cool.
I have an older DAC with hardware HDCD decoding (Sonic Frontiers). It has a light that signifies HDCD decoding or not. As long as I don't have an DSP going, HDCD lights up on an HDCD track. Obviously if I manipulate the signal at all (volume under 100%, DSP added, etc), the light goes off. I've actually used it as an indicator to getting bit-perfect audio.
Anyway...that brings me to my question:
1) With me using slight PEQ to fix a room node, would it be beneficial for me to use JRiver's implemenation of HDCD?
2) Any advantages/disadvantages of having JRiver do it vs my DAC?
Your DAC probably contains an HDCD chip. That type of implementation does a more complete job of decoding the HDCD encoding than most software implementations. In particular, the HDCD chip implementations has a filter stage that most software implementations do not have.
Without knowing the details of the MC implementation, it is hard to know exactly what they implemented. However, many of the software implementations are based on reverse engineering the HDCD algorithms, rather than a direct implementation based on knowing the exact HDCD specifications.
My recommendation is that the hardware implementation in your DAC probably is a more faithful implementation of HDCD than the software implementation.
That said, you need to decide if that difference is more important than fixing your room node issue.
I would listen to a well know track both ways to make a determination of the best approach to use.