First Watt J2

In addition to the helpful input from Almarg, you might also benefit from emailing Nelson Pass.  He does reply.

Get an SIT3...4 grand and it's yours! Note those supposedly work best with 4 to 8 ohm speakers.

@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’ve had several back loaded horns: CarderSound, Horning, Lamhorns, and Lowthers. Through trial and error, I’ve found they’re a much different animal than my front loaded horns, transmission lines, and conventional box loudspeakers. Like me, you may find a lot of what you thought you knew or how things look on paper quite different from how things work with these.

Although I’m not the biggest fan of the SET built around the bigger 211 and 845, they more than proved the best match with this type of loudspeaker, with the smaller SETs coming in next. The 211 and 845 simply put power into them in much better way, and came across as having much more seat of the pants power and better drive them than my push-pull tube, OTL, and solid state amplifiers