From the review:
" ... Lexicon merely took off the backside so it could fit the connectors flush to its own back plate, and placed a billet aluminum faceplate that sits over the existing Oppo button and VFD hardware. ..."
Ahh, if only they had done that much. But they did not.
Every seemingly thick lump of aluminum is not "billet". There may not even be anything actually called "billet aluminum", it's machinist shorthand for "a billet of aluminum".
The rule of thumb goes like this: if you don't tell your wife that you are "going to take a few thou of my beard this morning" you probably shouldn't be saying "billet aluminum" either.
A billet is a solid chunk of aluminum, that is then machined in a lathe or a 3-axis mill into some kind of part ... like a brake caliper. There is no need to use billet for faceplates ... especially when a much cheaper, readily available part right there in the catalog from your billet supplier is made for the job ... plate aluminum.
I would guess from the photos that the faceplate of the Lexicon hasn't been within a hundred miles of a milling machine. The holes appear stamped; you can see deformations around some square holes, which cannot happen from machine work.
The brushed aluminum finish can, of course, be done by machines, but generally about 15 seconds with a belt sander is how it's usually done in the shop, by the lowliest apprentice or the guy who otherwise sweeps the floor.
That may not sound like a high volume operation, and you would be right. Parts made from billets of metal come from low-volume machine shops that make them, automated for sure, but none the less with a real live highly paid guy running the machine, and then they end up someplace like on your ride from Washington to Bermuda, at 30,000 feet.
The phrase "billet [name of part] comes from the Harley-Davidson custom manufacturing that arose during the 1990's, which itself derives from the advent of CNC (Computer Numerical Control) machining equipment around the same time. That allowed machined parts to be automated, rather than being made 100% by operators, and brought down (somewhat) the price of machined parts to the point where the cost could be spread over hundreds of copies instead of paying for the machining of each one, at the same cost ... 1 or 1,000 (or 10 million if, perhaps, there's a war on).
CNC also meant a certain portability in the manufacture; you could send the data to another firm with the same equipment, rather than rely on using the same, trusted shop for your sources of parts.
At first, and properly, custom parts would be described as "made from a single billet of aluminum" (or any metal). There were always custom parts; you just had to know a machinist who took the time to make one for you. They weren't found by perusing glossy full page ads.
Later, larger volume production became possible, and mass marketing of "custom" machined parts began. Around 1990 or so, advertising copywriters shortened "made from billet" to "billet [wheel, caliper, doorknob, etc]". It's a phrase invented by office types who know nothing about actually making parts. I never once heard a real machinist refer to any part as a "billet [part]" before Madison Avenue introduced the phrase to the lexicon (no pun intended). It's a contradiction; a billet caliper is a caliper that is still a lump of square metal; being a caliper lies somewhere in it's future, and on that day, the billet dies and the caliper is born.
The brushed finish is done to hide the machine and tool marks; in the case of stamped plate aluminum, to somewhat take out the deformations left by the stamping process when making holes. There are a number of other finish options you can consider before you have to go to single-axis milling to make it flat and nice looking; some hifi does exhibit such faceplates ... some hifi does also have faceplates or chassis made from billets of metal. But, it's rarer than most people think ... most of the parts I see may have machining operations done to them, but are usually made from extruded metal (you push it through a die ... heatsinks, for example are extruded and cut to length).
Tellingly, these components with parts made from billet are usually very expensive and sell in the hundreds, or the dozens, or less, not thousands of examples.
It could, of course, conceivably be that the Lexicon faceplate is really made from billet instead of plate. However, if that were the case, we then should really back off of Lexicon on this one. After all, they would have left about 95% of the billet on the floor in chips of high quality, guaranteed purity and composition, tested and certified aluminum, and there's a lot of highly paid people and time involved.
If that's the case, there's the three grand.