Lightspeed Attenuator - Best Preamp Ever?

The question is a bit rhetorical. No preamp is the best ever, and much depends on system context. I am starting this thread beacuase there is a lot of info on this preamp in a Music First Audio Passive...thread, an Slagle AVC Modules...thread and wanted to be sure that information on this amazing product did not get lost in those threads.

I suspect that many folks may give this preamp a try at $450, direct from Australia, so I thought it would be good for current owners and future owners to have a place to describe their experience with this preamp.

It is a passive preamp that uses light LEDs, rather than mechanical contacts, to alter resistance and thereby attenuation of the source signal. It has been extremely hot in the DIY community, since the maker of this preamp provided gernerously provided information on how to make one. The trick is that while there are few parts, getting it done right, the matching of the parts is time consuming and tricky, and to boot, most of use would solder our fingers together if we tried. At $450, don't bother. It is cased in a small chassis that is fully shielded alloy, it gets it's RF sink earth via the interconnects. Vibration doesn't come into it as there is nothing to get vibrated as it's passive, even the active led's are immune as they are gas element, no filaments. The feet I attach are soft silicon/sorbethane compound anyway just in case.

This is not audio jewelry with bling, but solidly made and there is little room (if any) for audionervosa or tweaking.

So is this the best preamp ever? It might be if you have a single source (though you could use a switch box), your source is 2v or higher, your IC from pre-amp to amp is less than 2m to keep capaitance low, your amp is 5kohm input or higher (most any tube amp), and your amp is relatively sensitive (1v input sensitivity or lower v would be just right). In other words, within a passive friendly system (you do have to give this some thought), this is the finest passive preamp I have ever heard, and I have has many ranging form resistor-based to TVCs and AVCs.

In my system, with my equipment, I think it is the best I have heard passive or active, but I lean towards prefering preamp neutrality and transparency, without loosing musicality, dynamics, or the handling of low bass and highs.

If you own one, what are your impressions versus anything you have heard?

Is it the best ever? I suspect for some it may be, and to say that for a $450 product makes it stupidgood.
Given the utterly minimalist nature of the LSA in terms on control functions, etc. you would think they would not fear the rath of their advertiser - past, present, and future to have a $470 Class component that is what is, but not a full featured preamp that "justifies" the much higher prices of other Class components. But, alas.....
Looks like Morley muso's equipment has jumped on the Lightspeed band wagon as well claiming better sound than with normal foot operated volume pedals, pity it's mono otherwise it could have been utilised.

Cheers George
I've built the Lightspeed attenuator with the kit purchased from Uriah a couple of months ago. I'm pretty impressed. I love the utterly simple design! The sound is pretty transparent. It works pretty well with GTA tube amp. The only concern is the soundstage imaging which is not as good as before. Nevertheless it's an excellent preamp, practically free if you look at how affordable the kit is. Here's a picture of the completed unit.

My Lightspeed Attenuator

Kudos and congratulations to George for making Stereophile recommended component!
The only concern is the soundstage imaging which is not as good as before.Jylee

This from experience may be because it does not use the far more expensive NSL32SR2S (S=sorted)+(tighter impedance span) "quad matched" as in the production Lightspeed Attenuator.
Rather it use the cheaper NSL23SR3 (non sorted)+(wilder impedance span) units and only "pair matched". And from experience even though the channel balance is fair, the i/o impedances vary quite quite a bit compared (because of the wilder impedance span)to the quad matched NSL32SR2S, and yes from listening to these the sound stage image does seem suffer at the different points of resistances.

Cheers George