Using the OP's evaluation, whom certainly has the experiences and is by this qualified to share their assessment of the End Sound Comparison. Using there assessment only, it does look like there is very good insight into how the Two DACs are to show differences, which in this evaluation nothing was discovered to separate the DAC when End Sound has been listened to using the USB option as the Signal Path.
The OP stated " So, in listening to the LAIV for a few days, I could not discern a difference between my Cheapie $1 Grand SMSL D400ex and the LAIV Harmony. (So, yes, the Emperor has no clothes). I had both DACs plugged into my Preamp and had two Identical Streamers plugged into each Dac, playing in Sync the exact same Music. So, it was very easy to switch back and forth between Dacs and discern any differences. "
Looking at the activity of @cutthroat over a long duration of membership, I don't see anything in the report but a genuine description of their experience had. I do not believe a steering towards the longer term owned DAC as a prompt to increase a interest in purchasing is their agenda.
In a completely different Thread, a Post has been made where there is the statement " Perhaps a general warning is required - SOME OF WHAT YOU READ HERE OFFERED AS ADVICE IS ACTUALLY A SALES PITCH. " Again, I am of the belief this is not the agenda of the content supplied in this Thread.
In a different Thread I recently stated:
" Investigating alternate Brands or alternate methods to acquire a Product , where there is an intention to acquire a product that offers a particular function within the audio system. Will expose the Purchaser to products more than capable of being extremely impressive.
Even as impressive or surpassing the impression where the option to Purchase is to remain Brand Loyal and upgrade within the Brand. "
I would suggest the LAIV was not too sure of a Volume of sales for their Product, and erred on the side of caution, where pricing has been to cover low volume turnover, which was then to be a high mark up on the Retail Price.
Individuals who buy into Products that are priced for the current markets with Low Volume Sales / High Mark Up, are Customers to be most effected by diminishing returns that comes with their choice made for a purchase. It cost the OP $320 to have this valuable lesson made known.
I have done a short search of the Market and have seen the following used item prices, which in my case will be an Import to incur added shipping and a levy, SMSL D400ex @ £430 and the LAIV Harmony @ £1950.
Looking at the OP's assessment and the current purchase prices that are able to be seen, it does look like a DAC stands out for being a DAC of interest for the individual with a constraining budget, or not wanting great cost associated to a DAC they intend to utilise.