Thanks for the info all, so if I decide on the Xls, how do I get as many sounds as possible to work on analogue using reed switches? And do I require a power buffer to keep the sound ticking over and shutting down on analogue?
You will get some sounds played automatically, and general 'driving' sounds, which will change with loco speed.
There are two trigger inputs, which can be used to trigger sounds.. Usually, these are used to trigger whistle/horn or bell. - The LGB track magnet can be fitted into the 'four foot'. There is a magnet in it (to one side, where the 'LGB' is embossed). If the magnet is on the left, it fires one switch (this is usually the whistle/horn). If the other way round, the second switch is activated, sounding the bell.
This is your limit whilst the loco is on analogue power. - You need a fully digital system to allow the triggering of other effects.
Yes, you will need a power-buffer to keep the sound going (for a time) when analogue power is turned down to zero (or dirty track). Once the loco comes to a stop, the engine noise will be at 'tickover'.. After a short time, the loco will go through the engine shutdown sounds, and the sounds will end.