I just got an alert for a Copper EMIA Remote Autoformer for a great price!

I'm not associated with the seller.

I love the EMIA autoformer.

If you are interested make sure that your input and output impedances are a good match. Decware products are 47k and 100K input so should be a good fit for most Decware systems.

https://www.usaudiomart.com/details/649985649-emia-remote-avc-copper-version/

https://myemia.com/Remote.html

It was a smoking deal! I almost bought it just because it was such a good price.

I've been smitten with the autoformer since I first heard it. Yes, it is a "preamp" DAC and Phono go into the autoformer, autoformer goes to the Torii.

I find it far superior to any other volume control I've tried. I sold my CSP3 25th mods for one.

My brother sold his PS Audio BHK pre for one. To be fair we both agreed the CSP3 was superior to the BHK across the board.

I ordered my Torii with no volume pot.

The autoformer offers speed like I've never experienced before. Everything else sounds slow after having the autoformer in the system. The autoformer provides beautiful rich harmonics with that speed. Adds a bit of weight to the music too. If you have played around with a riding the gain the autoformer offers the same effect, at a "fixed" level.

When using the autoformer to attenuate it takes the voltage and lowers it at the same time increasing current. I don't know if this translates to some of the magic or not. A standard pot converts some of the voltage to heat to attenuate the signal.

There can be potential downsides. Impedance matching is critical! Fortunately Decware amps have 100k input impedance so all good on that front. Issues arise when the output impedance and input impedance are too close.

Just adding to the good info / intro about autoformers that GroovySauce posted, there are also transformer based pre-amps, which are basically the same thing, except the wiring is much more complicated.  I believe transformer based preamps (Transformer Volume Controls: TVCs) preceded the autoformer variety.  They both offer the benefits that GroovySauce mentioned -- notably, the capability to add current inversely proportional to the voltage drop, instead of tossing the extra energy away as heat loss.  One practical advantage of this is the ability to maintain dynamics and transparency with low level listening (low voltage levels)... I think the signal can be delivered with less resistive effects.  There are other benefits as well, but this is one of the main bullet points.

I think the main reason people migrated to using autoformers is that they perform just as well, but are much easier to wire... with transformers, a separate lead had to be run to a different point on the input winding, which correlated to a gradual change in the voltage : current output ratio as the signal jumps from the primary to the secondary.  The volume control was done via a selector rotary knob with maybe 20 or 30 individual 'stops', just like a stepped attenuator.  Each 'stop' on the dial needed an independent wire lead to a different place on the transformer, so there would be a bundle (or a tangled mess) of leads that needed to be kept track of and worked around, so it was labor intensive for the builder... and almost all TVCs were hand build using point to point wiring.

I said 'almost' all used point to point wiring, because there are exceptions; I have a recent version of a TVC that uses a PCB instead for the wire leads, which made for a cleaner and more organized build... I doubt the PCB sacrificed anything to sound quality, but it was at the expense of not carrying the sexy 'point to point wiring' badge.

Everyone has their theories about... well, everything... but for me, after a lot of research and experience with various pre-amp designs, TVCs and AVCs are at the top of the heap.