Just need to get your hands on two 2sk82 or 2sj28.
2sj28 you'd have to use a negative supply (as opposed to a normally positive power supply).
Everything is reversed for the negative supply. There's a schematic somewhere.
never heard a DTQWT. looking at Troels G's characteristic though, it shows a bit more roll off high up in freq than usual? an F5 amp might be a good match.
for horn setups though, F3 (or ACA) have been a popular choice. F5 vs. the latter two: these amps come from the two ends of the spectrum, the "accurate" end and the forgiving "musical" end. so if you build both you should appreciate the choices/difference. (mind you F3 had a lowish input impedance if I remember correctly).