Joule Electra preamp and Aragon 4004 mkII

I owned both of these pieces, but not at the same time.
The 4004 MkII is a very good value for the money and has held its value amazingly well.
The 4004 MkII has a low'ish input impedance of 22K ohms (similar to some Pass amps).
The LA-150 MkII has adjustable output impedance of either 400 or 1200 ohms.  Most believe a ratio (input/output impedance) of 20 or better is sufficient to prevent audible frequency roll-offs, and some say a ratio as low as 10 should be sufficient.  Your proposed combination should work fine together and you can experiment with the Joule's jumper to determine which output impedance sounds better.
One caveat, many manufacturers report the average output impedance or the value at a frequency of 1,000 Hz, while the highest value can occur at the lowest frequencies, particularly with preamps that use an output coupling capacitor.  Not sure about the Joule but in any case the 400 ohm setting should work fine for you.

You are welcome foster.
Let us know how they sound together.

Good catch Ralph.
I was not even looking at the speaker interface and simply got lost answering the Joule/Aragon compatibilty question - sorry foster.
If I were driving Klipsch speakers with a sensitivity of 101 db, I would look hard at a tubed amplifier such as an S-30 or the M-60 monos (both made by a pretty good company) or the First Watt amps (great recommendation) if SS were the goal.  The nice thing about high efficiency speakers is that the power then becomes relatively cheap.
I have long driven fairly inefficient speakers so have ended up with large SS amps of which the Aragon was a stop along the way.   If money were not the object, and I didn't need a bunch of power but wanted a SS amp, I would like to try the Class D SPEC amplifiers....but I digress.  
Will the Joule/Aragon combo work, yes, will it sound best with the Klipsch speakers, probably not for the reasons Ralph states, but it will sound good with other less efficient speakers.