speaker impedance

Personally never paid attention to ohms or sensitivity until I looked how they sounded. 
 

And remember it’s a nominal ohm rating - hence the importance of having an amp compliment your speaker choice. 

8 ohm, all other things equal

but they never, ever are equal

read: impedance curve of speakers... a single, nominal figure means very little...

music is not a handy dandy 1 khz sine wave

Well, if we are going to make an argument about distortion, it's good to take an example of a decent linear amp:

@bache @knotscott @erik_squires 

While it is true you can get more power out of a solid state amp driving 4 Ohms as opposed to 8 Ohms, the simple fact is that all amplifiers make greater distortion into lower impedances.

The distortion that generally shows up in solid state amps is of the unmasked higher ordered harmonic variety- to which the human ear is keenly sensitive! This means that the presentation is likely to be brighter and harsher, since the ear assigns that tonality to this kind of distortion. Distortion obscures detail; increasing it seems counter to the goals of high end audio.

In a nutshell, if sound quality is your goal your amplifier dollar investment is best supported by a speaker of higher impedance; if sound pressure is your goal you have a 3dB argument for going with 4 Ohms as opposed to 8.

4 Ohms has other disadvantages, for example the speaker cable becomes far more critical!

I've often heard the argument about how good a certain 4 Ohm speaker sounds; the counter to that is that same speaker technology would sound even better if it were 8 Ohms, not on account of the speaker but on account of the distortion being reduced.

We like to think that certain small increases in distortion is 'negligible' or 'inaudible'; such talk ignores how the human ear works, which is to say it uses the higher ordered harmonics to tell how loud sounds are, and so has to be keenly sensitive to their presence!

They make their own custom speakers.  Some of them can be very large!

@twoleftears  can you recommend any particular speakers brand that works with fleewatt avaliable in Deja VU 

If you're really serious about speakers that work with fleawatt amps, visit the Deja Vu website (the audio store in Washington DC, NOT any of the other ones!)

Are there any high impedance speakers out there designed with tube amps in mind? I see you can get 16 ohm compression drivers. A couple of 8 ohm woofers could be wired in series to give 16 ohm impedance. Doesn't seem to be a popular design choice.

Buy good speakers designed well and the designer will decide which impedance works best.

The only thing really important is their SQ. In a few cases you might find a better amp to drive them. 

They are about the same wiht any modern solid state amp.

I mean, in an ideal world, higher is better = low current and easier to drive, but from a practical perspective, impedance only matters a lot with tube amps or speakers that dip below 4 Ohms.

If upgrading speaker. Typically you want to find speakers that captivate you… ignoring requirements. Speakers are very important to your enjoyment and if they don’t captivate you it is unlikely any amount of changes in electronics is going to help that.

While typically 8 ohm speakers are “easier to drive” but there are so many variables… I wouldn’t let it drive your choice.

If you chose planar speakers (electrostatic or ribbon), they require a lot of power (current). Then you will have reason to pause and consider what other changes you may have to do.

Best find speakers that sound great to you… then see if your electronics are up to them.

Lower impedance requires more current flow from the amp.  As long as the amp has the ability to drive 4 ohms, it shouldn't be an issue.  Upgrade to something that sounds good to you. 😎