Если по USB, то ЗК не нужна, нужен внешний ЦАП с асинхронным USB.
Но по USB (кроме 3.0) будет ограничение - только до 24/96.
Остальное - дело вкуса.

Вот своеобразный рейтинг, можно брать за ориентир:

Weiss DAC2 $3000
DB Labs Tranquility $2400
DB Labs Tranquility $1500
Bryston BDA-1 $2000
Ayre QB-9 $2500
Naim audio DAC $3500
Audio-GD Reference-5 $1000
WYRED DAC2 $1500
WYRED DAC1 $999 
Audio-GD DAC-19 $640 / EE Minimax DAC $750
BEl Canto DAC 3 $2500 / Cyrus DAC XP $2200
Peachtree Nova $1200
PS Audio PerfectWave DAC $3000
PS Audio DLIII Cullen Mods stage 4 $1700 / Lavry DA-11 $1400 / Benchmark DAC1 HDR $1300 /Stello DA220 $1650
Lavry DA-10 $975 / Apogee miniDAC / Yulong D100 $500 / Havana $850
Stello DA100 Signature $995
Benchmark DAC-1 $995
CIA VDA-2 DAC $765
Nuforce Icon HDP $450
Meier StageDAC $700
Logitech Transporter $1800 / PS Audio DLIII $700
Musical Fidelity M1 DAC $700
Arcam rDAC $500
HRT Music Streamer II+ $349
Audio-GD Fun $340
Musical Fidelity V-DAC $315 / Matrix Cube DAC $270
Cambridge DACMagic $300
Audio-GD Compass 
Dr.DAC2 DX $300 / Zero DAC $180 / Audinst HUD-MX1 $179
udac-2 $129
Pegasus $130