Same watts at 8 and 4 ohms?

Your speakers don't look like they would be difficult to drive. They only reccomend and amp of 50 watts or higher. I haven't seen measurements of the 6t but stereophile has the 7t looks like it stays mostly between 4 and 8 Ohms. 

Frequency Response 35 Hz to 25 kHz ±2 dB, -6 dB at 30 Hz
Sensitivity 90 dB for 2.83 volts at 1 meter on axis
Impedance 4 ohms, 3 ohms minimum, low reactance
Power Requirements 25 watts minimum, >50 recommended
Woofers Dual 5.9″ (150 mm) with cast magnesium frames, special papyrus blend cone. copper pole sleeve, dual magnets, 1.25″ coil, long and linear Xmax
Midrange 4.8″ (123 mm) with cast magnesium frame, special papyrus blend cone. copper pole sleeve, dual magnets, 1.00″ copper clad aluminum coil
Tweeter 1″ (25 mm) with thick machined aluminum plate, soft ring-dome design with machined wave guide, dual-magnets, 1.00″ coil, copper pole sleeve
Crossover Fourth order acoustic Linkwitz-Riley, 600 Hz and 4,000 Hz crossover frequencies, 2 physically separate networks

n80 OP
I’m not saying to get the ML2’s, it was used as an example of what does drive speakers.

Your 7B’s drop to 3ohms around 150-200hz not too bad but still needs needs a bit of power there.
But! they are specified as 86db by Aerial, but actually tested by Stereophile at only 84db!!
I would look for a >100w-8ohm amp that can do tested doubling those watts into 4ohms and you should be fine.

Or you can get the $400 3000w Behringer and listen to that, probally not for long.👎

Cheers George

By tested do you mean what the manufacturer will publish (some don't give 4 ohm numbers) or do I need to look for an independent test?

By tested do you mean what the manufacturer will publish (some don’t give 4 ohm numbers) or do I need to look for an independent test?

Test is to me an independent "test" like Stereophile, Soundstage Measurments, Miller Audio Research etc etc.
As amp manufacturers "specs" sometimes/mostly fudge their specs.

If they don’t give the 4ohm wattage numbers, then either the amp doesn’t look good doing them(like the heading of the thread) or goes backwards even from the 8ohm, or it simply can’t handle it at all, and turns off or blows a fuse.
Look for reviews that give bench test also


Cheers George

Hi George,

Take a look at any speaker review on Stereophile and they will plot the speaker impedance.

This impedance is never a flat line at 4 or 8 Ohms and in fact take quite complicated shapes.

The lower the impedance, the more current the amp has to produce to maintain a stable output, otherwise it starts to drop.  If you think of a wall wart, 12V, 2 Amps.  If you try to draw more than 2 amps, it no longer produces 12 V but instead the voltage sags until it overheats.  Amps do the same thing.

An ideal amp maintains the voltage output regardless of speaker impedance, which is synonymous with saying it doubles the wattage as the impedance is cut in half.

You may not need an ideal amp or like how it sounds matched to your speakers though, so keep this in mind.  The C 388 uses a hybrid Class D designed by Bruno Putzeys (or nCore?) which is a pretty sweet little thing. It puts a linear amp in the middle of the Class D.  I have another NAD integrated with it and I like the sound a lot.  It's not as fun to listen to as my Luxman, but nothing wrong with it either.