Amps for KEF Blade 2

I am looking for advice from owners or dealers of the KEF Blade 2 loudspeakers. I am concerned my current pair of amps will not be sufficient for the B2s because of an article written about the original Blades published on July 5, 2013 in The Absolute Sound:

"The Blades have a nasty kick in their crossover that will suck an amplifier dry quicker than a student downing free tequila shots ... Just don’t be tempted to cheapskate on the driving amps, or you’ll live to regret it. Tube amps at least have an output transformer to hide behind, but when the Blades suck out a solid-state design, they celebrate by spotlighting their tweeter something chronic. To give you some idea of the lengths required, the otherwise excellent Rowland 625 [550 watts into 4 Ohms] wasn’t up to the job, it taking a pair of the 725 monoblocs [650 watts into 4 Ohms] to restore order. "

Are the Blade 2s just as demanding as the original Blades in terms of amplification? I would guess not due to the smaller 6.5 inch woofers, but this is just an uneducated guess. I own a pair of Benchmark AHB2 amps, which according to the manufacturer produce “a little over 500 watts into 4 Ohms”. Will this be enough?

Showing 2 responses by mmeysarosh

Stereophile has a full set of measurements on the Blade 2 and it primarily shows the speaker requiring full 4 ohm stability with an ability to be fully stable to a 3.2 ohm load. This will simply require an amplifier with adequate current capability. As an example, some of the older ASP1000 based amps did poorly with lower lower impedance speakers than their ASP500 counterparts on some speaker models. The reason was due to the first generation higher power amplifier apparently being less comfortable in dropping below 4 ohm than its lower specified counterpart.

In terms of the Rowland, it does specify near doubling of output at half impedance with the 725 mono blocks as compared to the 625. Most of this load is below 200hz and rises to 6 ohm nominal above it. This could explain the spotlighting phenomenon since we know the B2 goes as low as 3.2 ohm in this area. My suggestion is to try and mate amplifiers that offer 2 ohm stable output in order to prevent the amplifier going anywhere near its potential current reserve. One suggestion would be some of the Pass Labs models, as some are capable of power into 2 ohm loads without much stress. This factor is tough to know until you get the amp on the bench. Even then, there is something to be said about overall synergy.  
I did see some of the specs on their website and they do specify increasing power output at 3 ohm load, which indicates amplifier design with current capability in mind.

While the the power output isn't able to drive the speaker to its max SPL, my take being that you'll give up before either amp or speaker do.

Overall it sounds as if you have a capable partner. I brought up some of those ASP1000 class D amps as they doubled output going from 8 to 4 ohm impedance, but quickly fell apart anywhere below that. The speaker in question was the Revel Salon2, which is also current happy design with lower efficiency in comparison to the B2. So you really want to get a clear answer if the design can dip to 3 ohm or even 2 ohm. Which is was you do have with your current amp.