Question on Emm labs Dac6 vs Dac6e

I am considering to purchase a pre-owned Meitner separate, very much confused for the models, especially some has Dac6, some Dac6e, I know the latest are DAC 6e SE, can anyone tell me what is difference between Dac6 and 6e, is it significant as 6e to 6eSE?