Best used DAC under $750.

I have been happily using Bryston BDA-1 since 8 years. Currently there are atleat three offers on A’gone which can fit your budget ( under $700) comfortably.
Bryston gears are very reliable and long lasting. I would recommend to consider it.

If you are happy with redbook only,  then do your best to find a Wadia 15  It uses the Burr Brown PCM63 R2R architecture which beats, to my ears, the delta sigma DACs, unless you are prepared to pay huge money.

This on redbook is a more musical and rewarding experience than my Bryston BDA-1 playing hi-res.  The Wadia is built like a tank and can be found for about $700 to $1100

A friend brought his Theta over to compare. He went very quiet when he heard how much better the Wadia is.

Hello,

I’m about to upgrade and I have a Chord 2Cute which a great DAC. I will let it go for $600.00. You can send me a message or email me at tbrathw8@gmail.com

Jolida, now Black Ice,  FX tube dac for $550.  Awesome sound but no remote volume or input.    Search for the Arizona audio club shootout.

I second the Schiit Gungnir Multibit.  If you want MQA, find a used Mytek Liberty.