Sound Upgrade Recommendations

[RedMt Dave]

After purchasing a DCC sound locomotive, I want to upgrade my existing DCC-Equipped locomotives with a sound board.
I thought I would start with my Bachmann DCC-Equipped EMD GP40 locomotive that came with the Digital Commander set that I bought last year.
Is it as easy as removing the existing DCC board (H633Y+PCB01) and replacing it with a suitable replacement?
Also, I realize that this is a Bachmann forum, but could you make any recommendations on which sound boards you like the best.