The sounder is in the TZT3 and the DI box is a smart amplifier that builds upon that. Yes, it is true 3kw RMS sounder signal when the TZt3 and Di are combined with a properly matched transducer; when others on the market will use peak to peak measurements to game the system. Keep in mind the High freq on about any transducer is normally always 1 kw because it is the freq not the power is what is limiting it for depth. The “3KW” rating of the transducer is talking about the low side where the extra power provides benefit. It is hard to compare the DFF3 and the TZT3/DI unless running CW because the DFF3 isn’t Chirp. In CW, they would be very comparable but the TZT3/DI is much more flexible in allowing both Chirp/cw/ or a mix of both.