I had a QB-9 on loan for a month and later bought an Ayre Codex. I have the QX-5^20. It is fantastic. A lot depends on what system you have. I have a KX-5^20 and VX-5^20 plus Vandersteen 5As and the QX-5 is superior in that setup. The built-in Roon bridge gets an awful lot of use in this house. For other inputs, I have an Oppo-BDP205, toslink from a Samsung Q7FN (cable, AppleTV, or the TV itself) and a Raspberry Pi that serves as an Airport Express bridge (actually running Ropieee, a Roonbridge with shareplay compatibility) for quick and dirty streaming (still sounds good though). All sound great.