The new Tesoros have more gain than the older models, and also have saturated audio where the older models had modulated audio. The audio is basically full on as long as a target can be seen, giving the same volume on deep targets as shallow targets. That in itself doesn't add depth, but it makes the deeper targets easier to hear and creates the impression that more depth is achieved. The added gain does increase depth, but usually at the cost of stability and loss of target separation. Tesoro has apparently found a way to add gain and retain most of the stability as well as good target separation. I did a few tests with a Tejon and found it did as well in small ferrous trash as any of the older Tesoros I've used as long as the sensitivity wasn't set too high, actually it did a lot better than the Bandido II