DCC programing:  TCT has the actual programmers to handle most manufacturers sound files.  We adjust and taylor sound settings to give each model it's own character.  Thanx Thom...

Decoders:
The first requirement I have for selecting a decoder is space (will it fit)?  Next is programming sound files (does this decoder have the sound file that's best)? Lastly, lighting functions (which version decoder will give me the most lighting functions that's needed)?
 
Top sound decoders I like & recommend are: 
Loksound
Soundtraxx
Zimo
TCS

Each have pros & cons to installing, programming & operating.

Top function only decoders I like & recommend are:
Zimo
Soundtraxx
Digitrax
NCE

 Each have pros & cons to installing, programming & operating.

Speakers are any largest size I can fit and still get a good quality sound with the decoder I'm using.  TCT uses all types of speakers from cell phone to big bass.

more to come.