My question is: why do you want to replace the BLI sound board for? Those boards are designed for those locos and they have sensors on the cams to synchronise the chuff and so forth. The Tsunami doesnt have the link up for those sensors, it just guesses by the output voltage going to the motor.
So, why ruin a decoder that was designed for that particular loco?
And, all these folks talking Tsunami this and that. It isnt anything but another sound decoder. When you get 2 or more sound locos going at once, you won't be able to tell a tsunami from a $40 MRC sound decoder. That I can vouch for from experience.
Now, if you run one single sound decoder in a consist and get out on a long run, you can still only barely determine some of the sounds it makes. The only way this board is gonna sound great is in a loco that is on display only, and by itself.
Trust me, get some good deals on the decoders, and use what you can afford. For the price of one tsunami, you can get 2 MRC 1634 sound decoders, with some change left over, about $15-20 to be exact. Thats enough to buy a NCE D13SRJ 4 function decoder for another loco. Now, unless you got money just spilling out of your pockets and have to have the most expensive things out there, then conserve and you'll be able to buy more for your money.
Don't price yourself out of the hobby by thinking you have to buy these expensive decoders to be able to enjoy a particular loco. Unless you only plan on having a max of 10 locos in your stable, then spend what you think you'll enjoy hearing.
Now to answer your original question: If you have dcc decoders in locos, then you still have to have a command station to send the different commands out to the locos. A regular dc throttle will not activate all the available functions you'll have with dcc. And, getting BLI blueline locos with the right motor decoders, you'll have no problem programming them on either the NCE powercab or MRC Prodigy Advance2. I have 2 of the AC6000's from the first run, and I had LENZ LE1000W single function decoders in them for a long time. I changed them because the Lenz decoders have a high throttle to movement ratio that cant be adjusted in the cv's. I replaced them with NCE D14SR's that were a sinch to program on the main.
You don't have to buy a big system to get all the bells and whistles that you'll get with the sound decoders. A NCE power cab, and the MRC prodigy express/advance lines have at minimum 16 functions available to get the most out of those sound decoders. The other big name dcc system doesnt have anymore than 14 with the most expensive system, unless you get the computer adapter and install JMRI, and get the wireless handheld..... After spending about $450 or more, you might get above 14 functions with that system. For about $115, you can get the Prodigy express with 1.6 amps and 16 functions; or for about $175 you can get the NCE powercab with 2.5 amps and all 28 functions; or for about $210 you can get the prodigy advance2 with 3.5 amps and all 28 functions; plus you won't be tied down to a large throttle-command station and can get up and walk with your train with these systems.
So think carefully before you plop down all this money on this equipment. For the price of the dcc systems, you can buy a few more sound locos.
/rant