I have been using a ROMFX for sound for quite a while and I really liked it, but struggled to get enough volume from it. I upgraded to an Aker MR1505 amp but when I plugged the ROMFX into it, I wasn't happy with the audio quality .
Now I have discovered the Teensy 3.2 ( google it if you don't know what it is). With the added audio board it is fully capable of real time signal processing and playing back pre-recorded sounds either from memory or an SD card. The whole thing with the sound board measures a tiny 1.4 x 1.4 inches (35mm x 35mm)
I now have mine doing bandpass voice filtering rather than just distortion and static burst with just a hint of white noise to give a very realistic radio effect.
It uses the same programming environment as the Arduino, but it took me a little longer to learn just because it can do so much more.
I am just working on getting the power from the Aker to the Teensy and then the whole package will be a self contained voice unit, giving great sound quality and loads of volume.
Will post up some pics once it's done.
Wil.