I used to own a .5 and a DNA-1. I thought the .5 was a great little amp. However, I think there are better amps out there. For instance, I would recommend a Pass X-150 over the .5 or the DNA 1. Having said that, if you can get one for 500-600 on Audiogion, I think that is a good deal. I would note, however, that the .5 has some limitations. For example, you will not have a balanced connection option which for me is pretty important.
Good luck.
Good luck.