Why do you think your current receiver is inadaquate? Try it before you decide it's not enough.

Welcome to the forum.....

Your key is the Sensitivity of the new speakers compaired to your old ones......

Frequency Response: 45 Hz - 20 kHz
Peak Power Handling: 1000 watts
Program Power Handling: 500 watts
Nominal Impedance: 4 Ohms
Sensitivity (1w/1m): 100 dB
Connections: 2 x 1/4" Phone, 2 x Neutrik Speakon
Low Frequency: Dual 15" Woofers with 2.5" Voice Coils
High Frequency: 34mm Titanium Compression Driver with Exclusive Cerwin-Vega! HighRoad Horn
Dimensions (HxWxD): 46 " x 18 " x 19 "
Weight: 87 lbs.

Starting at 100db 1w/1m you will blow your head off before you run out of power.

Hi Mikeymad

I believe the problem lies elsewhere.he says he has a "750 watt" receiver.I bet it is a av one and 750w do not represent the true power.Best scenario would be 7x105 or better still 5x125.Even then,we are talking first for a 4 ohm loudspeakers and second about a av receiver.I doubt it has the current to drive the CV.Who knows how low the impedance drops in those loudspeakers.I have a friend with an old Yamaha 3090 av receiver that can't drive 6 ohm KEFs.
The prottection circuit keeps shutting the amp off at high volumes,let alone 4 ohm loudspeaker !

I agree Yiangos with all of your points.

But, I still have to say that these things only nead about 5-10 watts to get up to the 106db+ level. I would think that even a delicate tube amp could push them to a very high level. I don't listen to music much over 105db these days (very loud) myself.

I think that the ohm rating is an issue, but still, we are talking about just mustering up 1 watt or so to get 100db output. Most KEF's that I have seen are rated under 90db and can dip down to the 3ohm range. This would require a lot more current to get into the 100db range.

But we are talking about a av receiver here and a 4 ohm loudspeaker.There is no manufacturer that will say his speaker is 3 ohm right? let's suppose that this speaker IS a 3 ohm affair.Do you honestly expect a av receiver to drive it at all ?!?!?!? I bet the prottection sircuit will come on as soon as he turn it on lol
btw,my home theater amp is the top-of-the-line Denon.The manual states that the minimum resistance loudspeakers one should use with it,is 6 ohm ! In a few words,my Denon amp is supposedly able to drive something strictly minimum of 4 ohm.If he has a lesser brand/model,which i believe he has,how on earth is going to drive a 4 ohm loudspeaker with a pair of 15 inch woofers when by the time he turns it on,it sees something in the region of 3 ohm maybe less.

okay

If the receiver sees it as a short then there is nothing left to do (other than maybe throw a resistor in there).

Quote:
what kind of wattage in an amp am I gonna need to power these towers?

Back to your question. You may be able to use your receiver. But if you wish to buy an amp, it is not so much the wattage rating that the amp will need. The speakers are sensitive enough to run off of low wattage ratings. But as Yiangos pointed out with the very low ohm rating of the speaker it is the flow of power that is the issue. The lower the resistance, the more amperage.

Those suckers are rated at 1000W, so you could push them with a coffee table sized super amp, but look for a power supply that can push very low impedance ratings (down to at least 3ohms, if not 2ohm)