First, compared to other tube amps, I consider 845 SET in general to be exceptional contenders for superb musicality on a wide variety of speakers. So my comparative comments in response to question are just that -- comparative.
In isolation a Dehavilland 845 is a fine amp. Compared to some of the better alternatives, it has a consistently dry, desiccated character that isn't poor, but it lacks tonal body in a relative sense. I wanted intensely to prefer the Dehavilland, being USA made, but it just couldn't transport me far enough to an experience of musical integrity -- with any tube. And to the extent it matters, her industrial design is pitiful. It wouldn't cost any more to make a more visually-pleasing amp.
The Viva particularly, and to an extent the also-Italian Mastersound, has a vintage "slow" voicing of old school tubes. Shindo-like, which isn't to me a good thing comparatively. It is a big, voluable, romantic sound, but missing the speed, quick rise time and dynamic splash of the Audion and Sophia. Pleasant and rounded but not nuanced and vivid in a lifelike fashion. I am describing differences of degree. The NFA is more open than the Viva, but still sweetly flavored by comparison. The Dared, I think no longer made, is a sleeper at a low price, especially if the input and driver tubes are replaced with better NOS options. Based on all the rest of their gear, I have high confidence in the Melody Valve Hifi 845 SET monoblocks.
I've heard the KR 845 in some of these amps, the Shuguang 845 A, B and C in most. Also vintage NOS RCA and United. I've avoided the low-plate dissipation Full Music 845s. Consistently, the B tube is the value point, and quite reliable. I have a pair going on 7 years that still test quite strong.
The Japan-sourced Tri (Triode Corp) also has old school voicing, but i am certain all of these amps can be further voiced for more realism by re-capping the power supplied. I recommend Bob Hovland for this kind of exploration.
Phil
