Tube amp and speaker impedence matching

I recently purchased a Conrad Johnson CAV-50 and am actively looking for the "right" speakers. I found a couple of speakers (GMA Europas for one - rated 4 ohm) I would like to purchase, but I am concerned about presenting my amp with an improper impedence match and causing damage. The CAV- 50 is rated "45 watts per channel from 30 Hz to 15 kHz, both channels driven into 4, 8, or 16 ohms". I'm pretty new to all this so any help will be appreciated.
I would be more concerned with the efficiency.It appears that 3-4 ohms and up will work fine.Try to find a speaker with 89+ db efficiency and preferably a 8" woofer.The larger the woofer,the more power it will take to control it.
Improper impedence matching will cause roll off, not damage. Unless you plan to listen to music really loud this amp should work with most (not all) speakers. The exception would be if the speaker had an impedence dip down in the area of 2 ohms - this might cause a problem. Ask the speaker manufacturer. He is a fairly straight up guy - I'm sure he will tell you if your proposed match will work.
I don't know about these speakers but 4 ohm thiels drop to less than 1/2 that which can cause problems and distortion.
Europas are 4 to 5 Ohms for most of the audible band- no lower than 4 Ohms. Very resistive load, and very little back-emf from them makes your power just fine, in my experience- loud enough to have to turn it down to converse in any room smaller than 600 sq. ft, even on recordings with very high peak-to-average levels.
Roy Johnson
Green Mountain Audio
I guess impedence is the 'dirty little secret' of the speaker manufacturers. I own Martin Logan Aerius i's which are rated at 4 Ohms (Nominal- that's the White Lie), but the actual impedence drops down to 1.8-ish in the upper high frequency area!! Requested ML to provide the impedence curves and they gracefully declined.
Cdilascia, for being new to this you are pretty smart to catch on to this concern so early in the game. I didn't figure it out until after making some poor purchase choices, but now this is one of the spec areas that I actually pay close attention to in speaker and amp reviews and spec sheets. But often the warnings given are vague: "The MamaMia speaker loading drops down to X.x Ohms below 125 Hz -- be sure and match amplifier carefully!" It's great that I know to be "careful" if considering the MamaMia speaker, but not quite great enough because I don't know exactly what precise values I need to look for in a partnering amp to achieve a good working combination.

Let's say that I get the preference of the speaker manufacturer for which amps are well-suited to drive his speakers, but for whatever reason, I don't like the suggested gear and want to consider other offerings. Does anyone know of a good set of reference tables available which match various speaker parameters with good and bad parameters for amplifiers? Or should we just find a trusted EE friend every time we want to be sure, and feed him whatever specifics the companies (except, apparently, ML) will provide us?
If you really like a speaker that has too low an impedance, I have a couple amps that handle as low as 1.2 ohms with 120 watts-tubes. Let me know if you need new amp suggestions. You can sell the CJ easily.
Thanks for the complement Brett44! And thanks to everyone who has responded, including Roy. I have learned a great deal and the information has truly helped me make a sound decision. Elevick, I'll let you know after I have spent some time with the CAV 50.
I just auditioned the C-J CAV-50 with Joseph Audio RM7si Signature MK2 loudspeakers (stand mounted monitors) and this combination was very musical and three dimensional in its presentation. The Joseph Audio monitors disappeared when I set the volume of the CAV-50 anywhere between the 9 o'clock and 11 o'clock positions. This combo got loud at the latter setting, but never became fatiguing. The EL-34s were pumping out all of the tube glory with these monitors and I could hear some things on some CDs that I never heard before. All I can say is that the sound was much bigger than anyone would expect from this combination. The depth and placement of instruments went beyond the outer edges of the speakers, and I can only imagine what a high quality analog source would have done to me (used an Arcam CD player). Anyway, this combination doesn't go very deep into the low end, but what was there was tight, controlled and adequate for my tastes. One could easily get carried away playing the "air bass", acoustic or electronic. I listened to Santana's "Caravanserai", Diana Krall's "Live in Paris", Miles Davis' "Kind of Blue", Bill Evans' "Portraits in Jazz" and an assortment of other jazz and pop recordings. My schedule kept me from listening to chamber orchestra music or large symphonies, but I have an appointment to do so in the near future. The Joseph Audio monitors have a unique "Infinite Slope" crossover design that makes these speakers great, but they also need good cables to match them well to the CAV-50. I listened to this combo with Synergistic Technologies' active cables. This system is great if you just want to sit back and enjoy music rather than painstakingly analyze the sound of the system. All you hear is the music, and that's what I enjoy about this hobby the most.