4 ohm. > 89 db.

Is your question; "Are there other loudspeakers out there"?  Yes, there are. 

I agree with @russ69 -- not really sure what your question is about. There are a LOT of factors beyond impedence and sensitivity to consider when picking a speaker.  The first question -- have you heard these?

I agree with those above. What are you getting at. What system do you have?
 

I have Sonus Faber Amati Traditional 4 ohm 90db sensitivity. I think most Sonus Faber are about that.

Or do you want them to play that loud… mine will.

@jpwarren58 

If you have a choice, 4 Ohms is a harder load for all amplifiers and as a result they make more distortion driving such a load. So if the speaker could be made to be 8 or 16 Ohms without otherwise changing it, it would sound smoother and more detailed because the amp driving it would make less distortion. Distortion obscures detail and usually adds to harshness and brightness.

If the speaker were 95dB instead of 89dB you would need 1/4th the amplifier power to make the same sound pressure. Also worth noting!- if the speaker is rated 4 Ohms and 89dB, to translate to efficiency rather than sensitivity (efficiency is 1 Watt at 1 meter, while sensitivity is 2.83 Volts at one meter; so if 8 Ohms both are the same but at 4 Ohms they are not!), it turns out that the 4 Ohm speaker has an efficiency rating of only 86dB!

If you want the best sound, its a good idea to not have the amplifier work hard for a living!

Thanks for the replies. I was looking for comparable speakers. 

Since this post I have warmed to my amps ' sound characteristics . I have a large room and my 4 speakers lack the size and air to fill the room. Plus my amp is reaching its max in the attempt. The Modwright Integrated with Watkins 4, Kef Ref 3, Ryan 601, and Kef LS50.

I am continuing to search for more efficient speakers buy also contemplating two subs. However the more I listen the more I appreciate the amp.