Thanks for your above suggestion regarding the Music Hall 599 DAC. It was on my list.
Since my Ayre AX-7e amp is balanced, I wanted a balanced DAC priced under $500. After weeks of searching, I purchased the Musical Fidelity M1 DAC. This is an $800 DAC on sale for $499 delivered. See (you might need to copy and paste this link into your browser):
http://www.musicdirect.com/p-53380-musical-fidelity-m1dac-a-digital-to-analog-converter.aspx
The purchase of the Musical Fidelity M1 DAC means I can keep my Ayre AX-7e amplifier (home theater system). That is great news since I like it very much.