We drove the bigger easier to drive JBL 1400 with a pair of 60w OTL Monoblocks, and they farted away at anything above low to normal listening level, so stay away from them, I’d probably stay away from SET too. To be safe go with push pull tubes Ultralinear with at least 50watts with 4ohm tap. Or high biased solid state amp around 100w would be nice also.
Cheers George
In addition, the 1400 Array is an easy load for the partnering amplifier to drive, with an impedance magnitude that remains between 6 and 8 ohms over almost all the range above 200Hz, with a low electrical phase angle (fig.1). However, a minimum value of 4.8 ohms at 103Hz and a combination of 6 ohms and –52° phase angle at 71Hz will mean that the amplifier needs to be comfortable driving a 4 ohm load.
Cheers George