Ordered a Willsenton R300

Good for you.   I note that my expected delivery time period is between 11/10 and 11/29.  

Do you think the R300 can power Kef LS50's?

@voodoolounge 

I wouldn’t recommend it. 85 db sensitivity and behaves as a 4 ohm speaker impedance load per Stereophile.  You will not get near the true capability of what the 300b SET has to offer. This pairing favors neither the amplifier or the speakers. See below.

I used DRA Labs' MLSSA system and a calibrated DPA 4006 microphone to measure the KEF LS50's frequency response in the farfield, and an Earthworks QTC-40 for the nearfield and spatially averaged room responses. My estimate of the LS50 Meta's voltage sensitivity was 84.5dB(B)/2.83V/m, which is the same as that of the original LS50 and within experimental error of the specified 85dB.

The solid trace in fig.1 shows how the Meta's impedance magnitude varies with frequency. Below 200Hz, it is almost identical to that of the 2012 LS50 (fig.2, solid trace), but at higher frequencies the impedance traces are quite different. The Meta remains closer to 4 ohms for longer in the midrange but has a considerably higher magnitude in the crossover region. The new speaker's electrical phase angle (fig.1, dashed trace) is occasionally high, and I used the formula in a 1994 JAESpaper to calculate the "equivalent peak dissipation resistance" (EPDR, footnote 1). The LS50 Meta has minimum EPDRs of 1.66 ohms between 135Hz and 140Hz and 1.7 ohms between 660Hz and 725Hz, both regions where music can have high energy. The partnering amplifier needs to be comfortable driving 4 ohms.

I was an early purchaser of the LS50 and I struggled to make them sing with a 175 wpc Plinius SS integrated amp.  I agree with Charles1dad that the R300 would not be a good match. 

I don’t know a lot about the JM Reynaud Audio speakers but I am aware that they are generally said to be amplifier friendly speaker loads and match well with many tube amplifiers. So the likelihood of success with this 300b SET is reasonably good compared to the KEF LS50. Particularly in a smaller space at normal/moderate listening levels. Could work out very well.

Charles