I have the JRiver settings in 'Client Options' set to "Don't convert" and "PCM 24bit".
Just to be clear, this should be set on the laptop (your client), not the PC (your server). Is that correct?
I have DLA Server Audio set to " Mode Original" and "Format PCM 24 bit". In the "Advanced" "Stereo Downmix" is checked and not able to be unchecked.
These settings are for using MC as a DLNA server to other DLNA devices. They are not used when streaming from MC to MC on 2-computers. Client Options on the laptop are the settings you need to look at.
In Options -> Media Network, do you have Use Media Network and DLNA Server, DLNA Renderer, DLNA Controller checked on both computers?
On the laptop, I'm assuming your Audio Device is set to SPDIF Device [WASAPI] (Device settings need to have Event Style unchecked if you are using the new driver (12/12/12) and checked if you are using the archived driver).
Also on the laptop, look at Output Format in DSP studio to make sure it is not downsampling any sample rates to 44.1.
If you are playing the same high res file locally, it is not the last two issues, but just double checking it is not a difference in sample rate between what you are trying to stream and what you tested locally.