My honest opinion is that what you are proposing is overkill for the system you have. Save your money and use plain 12 or 10 gauge Romex; it should work just fine. Even if you upgrade your system later on, IMO you will still be ahead of the game. Lee at Cryoparts has Furutech FP-15A audiophile grade receptacles for $50.00 each. Another alternative is a Pass & Seymour 20A or 15A silver plated cryoed outlet from Dedicated Audio at $45 and $40 each respectively. Either one will work on a 20A circuit. The NEC allows a 15A duplex receptacle to be installed on a 20A circuit. 15A and 20A receptacles have the same current carrying capacity. The only difference is the T shaped neutral slot of the 20A receptacle is to restrict 20A rated equipment to only be operated on a 20A circuit.
For my own dedicated 20A circuit for my 2-channel system (listed below) I use individual 10 gauge type THHN/THWN wire in conduit, terminated with a Furutech FP-15A silver plated outlet (now discontinued). I also have a separate HT/secondary 2-channel system operating on another circuit wired with 12 gauge armored cable and a Leviton 15A industrial grade outlet.
System:
Denon DP-59L TT, modified, with ATOC9 MC cartridge
Marantz Reference SA-11S2 SACD player
Classé CP-50 preamp with phono, modified
Classé CA-300 amp, modified
DIY balanced power conditioner with surge protection
PSB Stratus Gold i speakers
Acoustic Zen Silver ICs, speaker cables and power cords