I went from the JA-100 standard edition to the JA-50 luxury edition monos. While having sacrificed a little bit of power, (the JA-50's actually produce 80 watts class A), the improvement in sound quality was evident. Aside from looking 10 times nicer, they sound smoother, more seductive, equally effortless and more musical. It's been a long time since I've owned tube amps, but the 50's remind me of the big, 'feel good' nature of tubes, without the hassle. Plenty of detail, great soundstage front to back, top to bottom, left to right, nice solid musical bass. Never looked back. I regretted having sold some nice mono ss Electrocompaniet amps years ago, but found that groove, and then some, with the Jungsons.