[borism]

The 0.4 V sensitivity is a number from the Bottlehead site. The folks at Bottlehead seem to be quite serious about their engineering. Paul Joppa, the designer of the Stereomour is very accessible on the Bottlehead forum and is probably the best person to address any question. 

[Canada Rob]

By the way:
When I ordered my Decware I did not mention my speaker or the output impedance I wanted, so I guess he supplied me the standard, which is 6-16 Ohms.

The SE84C+ only came with what is currently the 4 ohm option offered for the Super Zen.  There was no 6-16 ohm option offered on the Decware website for the SE84C+.

[Gihan83]

Hi Beano,

Yohan here from Singapore, I have a Decware super zen amp, if you want to test just drop me a message. I can guarantee that this amp is amazing, a very musical amp.

[Audiophile58]

I have tried hybrid amps, SET amps and class  ab triode Pentode
And even though there is no Xover the impedance can fluctuate as high as 11 ohms or a low as 4 ohms. Depending on what kind of music playing and volume which determines frequency and demand on amplifier
The majority of the time the speaker plays in the 6 ohm range from tests we have done.

4 ohm taps has a better fleshed out midrange with better Bass weight.  At 8 ohm taps I thought it had a bit more  Air on top , at the expense of  Midrange depth which is where the heart of the music is.
4 ohm taps  seems most of us agree on . If a amp is real tubey heavy sounding and slow ,they I think the higher  ohm setting  May help.

[seikosha]

I've got the new SE84 with the UFO transformers which allow you to change the impedance from 4 to 8 ohms on the fly.  With the Omegas, I'd be hard pressed to say one sounded appreciably better.