While I have in the past worked with superconducting stuff for data converters, microwave filters, and computing, I am no expert. There are a lot of practical complications to deal with in bringing something like that to the consumers. Heck, there are a lot of complications bringing it to any application...
For RF systems, I have dealt with noise floors for narrow-band systems in the -140 to -160 dBm (mW referenced to 50 ohms) range. Audio is a piece of cake.
You need to specify what metric is used for "performance". For data converters, ENOB (effective number of bits) is essentially SINAD. A perfect converter with no noise except quantization noise has SNR ~ 6N dB for N bits. The noise floor is about 9N dB assuming no other noise or distortion. If you "add up" (root-sum-square, RSS) all the quantization noise across the Nyquist bandwidth that 9N dB noise floor becomes about 6N dB of SNR.