Hi,
I listened of my new purchase an Moth S2A3 with rectifier tube on top since 1 weeks.
I owned many high amp like Woo WA5, Balancing Act 300B, DNA Stratus and 2A3MKIV.
The amp was completely cleaned, checked and recapped. I use Sylvania or RCA 2A3 dual black getter, Amperex GZ34 and Roger ECC35.
IMHO it's a marvellous amplifier. Honestly I didn't like the 2A3MKIV and DNA Stratus with the HD600 as the sound were too ethearal, thin with tizziness in treble.
The Balancing Act where smooth and fluid but a bit distant, I didn't have the best tubes for it so I cannot hear him at his best. The WA5 was a bit harsh and overpriced.
Hearing the HD600 on the Moth it's hearing another headphone, more body, heft, smoothness and openess. The Moth is a bit more intimate sounding in the sense less distant than the others amps I owned. In the same time it has more openess because each sounds has more depth and intensity.
To sum up it has an textured thick sound with solid bass foundation, speed and heft with smoothness that removes tizziness. Also it has unique lively and vibrant sounds that let you to travel into the music.