Achieving a playback rate of more than 10Mhz will either be extremely difficult or impossible with an 80 MIPS processor without some sort of extra hardware to manage the sample-memory-to-DAC pipeline. (At 10Mhz, you only have 8 instructions to get each sample out of RAM, out of the chip and into the DAC, and detect if you're done with your loop.)
But are you sure you're thinking this through? Let's say you filled up all of a PIC32MX795's RAM (128K) with the samples you want to send out. At 10MHz, that's only 13 milliseconds worth of playback. In other words, you will only be able to play back 0.013 seconds worth of data at 10Mhz even with maxing out your sample space in RAM.
Also, a 10MHz analog signal is considered 'high-speed'. This means you'll need a custom board made, with careful attention to all of the high speed analog circuit board routing rules, decoupling, output buffering, etc.
So, is 13 milliseconds worth of playback going to be enough? If not, then you need to go slower than 10Mhz, or you need more sample space.
If you need more sample space, you will need to think more about how you're going to store your samples. If you really need to play them back at 10Mhz or higher, the only thing I can think to economically store them is SDRAM or DDR RAM or something like that. To interface with SDRAM or DDR RAM and be able to get samples out at 10Mhz or higher, you'll need a dedicated hardware memory interface. You can construct one in an FPGA, and then communicate from the PIC32 to the FPGA through SPI or some other communications bus. The FPGA could then very accurately time the samples going out to the DAC, and could interface with very large memories, and could play back samples at much higher rates than even 100Mhz if you got a fast enough DAC.
But writing the FPGA code to do that would take quite a bit of time. For somebody who knew what they were doing.
The FPGA method is how the commercial arbitrary signal generators (AWGs) do it, I believe.
So maybe you can give us more information about what type of signal you're trying to play back, for what purpose, and think about how fast the samples really need to be, and how long your maximum playback time needs to be.