Dual mono, 6 channel a side single ended triodes direct driving (no crossovers) a ribbon tweeter, three horns 100Hz/250Hz/400Hz, sealed bass channel plus a spare channel for mid-bass once room integration is complete. All channels circa 110dB/w/m except bass which is 100dB/w/m.
Room response is flat to 18Hz. Bass channel presents a 1.1ohm load and is driven by 9w SET with enormous custom wound output transformer. Channel gives full 9w power with -1dB roll-off at 6Hz. Other SET channels are a mixture of two stage, DHT and single stage depending on the transducer they are driving with outputs of 1.5w - 17w.
Compared with single SET amps driving a particular loudspeaker system, or even SET amps with bass passed to other amplifier, there is absolutely no comparison...the failings of SET's in those systems just dissapear with multiple channels free of interference from the others. Direct driving the transducers really helps here as well. Soft bass, dynamics so real and transients so right with energy and time to spare. Dead quiet with my head in the horns, a soundstage and imaging that is immersive and more detail retrieval, intonation and fleshing out of sounds than many may think possible but not bleached or bright or fatiguing. I often listen 10 or more hours day while working. Loud.
The true beauty of this system though is that there are no distortion or other cues to tell you to stop turning it up. Listening at concert levels (i.e. 105dB peaks) is wonderful regardless of genre of music but you can go higher if you like. True to the Fletcher-Munson or Equal Loudness curves, the louder this system plays the softer the music sounds because it is actually capable of scaling up the bass with the mids and treble into spl territory where we can actually hear the bass frequencies as well as just feel them.
Not for everyone though. System weighs more than my car.