Wavelength Proton DAC: Battery Replacement

I'm getting drops in my music which I believe I've hunted down to a dying batter in my Wavelength Proton DAC. I've used my Proton as my regular DAC (about 4 hours a day) since January 2012 when I bought it. Given I'm going to replace the battery, does anyone have a recommendation of what to use? Obviously, I can disassemble it to find out what the stock battery, but wondering if anyone has tried any other battery alternatives for better results.