First Watt J2

@Kalali, yes, it is certainly understandable that the maximum power ratings of the two amps into 4 and 8 ohms would be misleading as to which is the current source amp and which is the voltage source amp, since **usually** doubled maximum power capability into halved load impedances signifies a voltage source amp. But as long as an amp is operated within the limits of its maximum voltage, current, power, and thermal capabilities, how its power delivery varies as a function of load impedance will depend on its output impedance, not on its maximum capabilities.

Also, it’s interesting to note that as indicated in its manual the power capability specs of the F2 are based on total harmonic distortions of a very high 4% for 5 watts into 8 ohms, and an even higher 9% (!!) for the 10 watts into 4 ohms. While the J2’s specs are based on 1% in both cases.

Best regards,
-- Al

I think that you've interchanged the mentions of the two amps. The J2, with its 0.4 ohm output impedance, behaves pretty much as a voltage source. The F2, with its 15 ohm output impedance, is the amp that behaves as a current source.

But to answer your question, while I have no experience with these amps, I would approach this endeavor with caution. See the following paper by Nelson Pass, about current source amps:

http://www.firstwatt.com/pdf/art_cs_amps.pdf

Note the many examples in which various passive components (resistors, capacitors, and in some cases inductors) are paralleled with the speaker to optimize sonics, with the values of those components depending on the particular driver. And note this statement in the conclusion section of the paper, especially the reference to "electrical networks":

Current sources and amplifiers with low damping offer interesting possibilities for improvement with these [full-range high-efficiency] drivers but they require considerable work to get the enclosures, electrical networks and acoustic environment just right.

Best regards,
-- Al