I recently installed a sample of the new Dallee Hi-Line sound into an RS3 demo loco.
Dallee has Hi-Line sound for Diesels, Steam locos, RailCars and Electric locos.
Each as has multiple choices of Bells, Horns -/ Whistles & Prime Movers etc.
Lots of programmable choices.
Installation in my battery R/C demo loco was straightforward. Volume can be controlled from a function on the TX handpiece as can the programming.
Can be used by regular track power (has super caps for back up) , Battery R/C etc.
R/C control of Whistle / Horn, Bell, Forced Notch 8 and programming / volume.
I am impressed. A quantum leap compared to the non Polyphonic sound Dallee used to offer.