Sadly, it looks like Spark Lights is now shutdown which is unfortunate. I was a fan of the of their 2xAA headlamps and picked up their SD52-NW several years ago. I still have this on my desk right now as an easily accessible headlamp for any small tasks. Its output is decent for an AA light (I think 260lmns max) but is pretty low by today's standards but runtime is good enough that it's still usable.
If the OP is looking for AA lights, esp in all-metal bodies, you will have to look elsewhere. Thrunite Acebeam, Sofirm, Fenix, maybe even Zebralight (if you can get a hold of one).
If you're interested, I have a Spark ST6-460NW headlamp I can sell you. It takes 18650 cells, has four "daily" levels (plus one turbo level), mode memory, XM-L T5 neutral white emitter, and clear (not frosted) SCHOTT ultra-clear lens. There is very little run time on this one, less than two recharge cycles worth. The light is virtually new and unblemished. I had intended to use the light on night hikes, but I went with the Fenix HL60R instead (broader beam, making it more useful in the woodland environments I typically hike through). The Spark was used only around the house.
Although it's discontinued, Going Gear has a good description still up on its website, and there are several reviews of the light online (a simple search...all will be revealed).
Send me a note if you want to have a conversation about this.