recommendations on a good used cd player for under $750

Look for an Oppo BDP 95, used they go from 600.00-800.00 on the used market. Run it in Pure Audio Mode with either Variable or Fixed Output. Sounds awesome and you can play concert BDVD through it with awesome sound quality!

just my 2c

Anyone- Marantz DV-9500/9600 ?

still expolring options and opinions? this is a 2nd system

Try Rega Planet or Apollo. I sold my Rega Planet not long ago for $250 which I paid almost $1,000 when I bought it. It worked perfectly and sound very natural.  

I've bought a lot of used gear over the years but one thing I steer clear of is anything that uses an optical drive...... The Marantz players are good,  l just bought an OPPO 103D to use as a universal transport and it's a great machine.  I use it with a DAC but often times I use it's analog outs to take advantage of it's variable output and to listen to HDCDs and it sounds pretty damn good as a stand alone unit.