dsPIC can be programmed with C, Microchip provides a free C30 compiler you can download. You're going to have to learn something here.
Programming dsPIC in assembly is far simpler than PIC16 series. First off all operations are done in 16-bit word mode unless you specify byte mode. For audio 8-bit is generally far too crappy so all your operations need to be in 16-bit. Second they increased the number of addressing bits to include all of RAM so the memory accesses don't need a paged mode. So aside from the fact that it runs instructions 4x faster than any other PIC, taking 2 16-bit numbers out of RAM, adding them together, and storing the result might be as little as 3 instructions, whereas PIC16 takes a lot more.
There's two 32-bit accumulators. These have most of the capabilities of the 16-bit working regs but also some new ones. Such as if you add 2 16 bit numbers together and the result is greater than what a 16 bit number can hold, you can set a AccConfig bit to say that when you move the data out of the accumulator it should read max value for the scale (0xffff if unsigned int) instead of some meaningless wrapped value.
But the features such as the accumulator are not required. I mean you can start by coding with working regs, you can even stick with 8-bit mode if it makes you feel better, and it'll be pretty much just like a PIC16.
You should be able to order the 33F (I recommend 128GP706 or 64GP706) off of Microchip's web site. Or Mouser. Or Digikey. Unless this falls under Export Restrictions there should be no problem getting ahold of them.