Oomph or pressure?

I have an Intact Audio autoformer that uses the same autoformer as your Emia (assuming you have the copper version, not the silver).  And I also have an Emotive Audio Epifania linestage (modified) which uses a single 12B4 tube per channel.  Coincidentally I have been comparing the two over the past few days for the first time since I got the autoformer last fall. 

In my case, the autoformer and the active linestage sound very, very similar with regard to tonal balance, detail and dynamics.  In terms of tonal balance, the autoformer has a little more weight in the bass and the upper midrange is a bit dark sounding; to my ears the Emotive is just about perfect in tonal balance.  The Emotive has somewhat more refinement and delicate detail in the highs, and it has a more involving, propulsive sound.  The autoformer has a lower noise floor (as in next to no noise).  These specifics aside, on an overall basis the active and passive sound remarkably similar.  

In particular I have not noticed any lack of dynamic "oomph" at lower volumes.  That makes me question whether your source is able to drive the autoformer properly.  I have much experience over the years with resistive passive attenuators and they do have the dynamic reticence that Ralph describes above.  The Emia autoformer does not suffer from that problem.

All of the above is In My Opinion and In My System of course.

Charles, I think you got the names confused.  The active preamp is the Emotive Audio Epifania so nothing inappropriate in its name.

I should emphasize that the Emia autofromer is very good by any standard.  I am somewhat splitting hairs by focusing on the differences. 

One final point.  It will take a very good active linestage to surpass the Emia/Intact Audio autoformer.  In my case, the Emotive Epifania started out as an excellent sounding preamp, but I have tweaked it to death over the past 10 years by swapping out different resistors, capacitors, chokes, and wire to find the best sounding combination.  I also eliminated the switching so it is a dedicated single-input linestage.  When I got the autoformer I followed the same approach---no switching, just a single input, and the same wires that I settled on with the Emotive preamp.  So they each have some advantage over your typical commercial products.

The term “passive” is an unfortunate one since it includes both resistor-based attenuators and magnetics such as transformers and autoformers.  The complaints often leveled against “passives” relate to problems with dynamics and drive, as others have mentioned, but those complaints pertain to resistor-based passives, not magnetics.  At least that has been my experience.

The OP, however, raised similar complaints about his autoformer, something I have not experienced with mine or heard about from other users.  That’s why I questioned whether he may have a problem with inadequate drive from his source.

Clio09 - You have more experience so maybe my generalization was wrong.  The Emia/Intact Audio autoformer is the only magnetic attenuator I have tried.