new GAN amplifier

georgehifi,

Considering most tube amplifiers with transformers, which many audiophiles love, and use regularly even with hard to drive speakers, have a damping factor <=20, your overall argument at least w.r.t. listening enjoyment is questionable.

If you look at the amplitude response curve and impedance curve, you will notice throughout the base, they are somewhat inverted. So the amplifier will not act as a "tone control", it will act as an equalizer to smooth out the response. That may not be a bad thing euphonically.  Are you 100% certain that low damping factor is always best?

arty_vandelay,

Please compare data for your favorite top A/B amp U-LD Mk4, given by the creators at www.siliconchip.com.au (August 2015) and the newest D-class from Bruno Putzeys - Purifi 1ET400A (www.purifi-audio.com). The D-class beats the A/B in all major categories. THD+N 20-20kHz is better with Purifi at 10W (ten) than with U-LD at 100W. From your coveted 5kHz, Purifi stays at 0.00029% (up to 20kHz) at 10 (ten) WATT and U-LD reaches 0.0008-0.001% at 100 WATT! The tough 18kHz+19 kHz intermodulation figures are given only by Purifi, AFAIK. But this is all academic. Both amps are an overachievement for the human listener, appreciated mostly by AudioPrecision analyzers which are not precise enough for some of their metrics.
PS. The U-LD amps are not on offer any more, are they discontinued?

The LKV Veros PWR using the Purifi 400A modules with a Class A front end sounded wonderful at the Capital AudioFest driving Sonner monitors, great first exposure to Bruno's latest module!