A lot of USB audio class 2 compliant DACs use the XMOS chipset.

Sagittarius has compiled an overview.

The information below is as supplied by the manufacturers website.

XMOS XS1-L1 USB Audio 2.0 US$ 149.00

• USB endpoints use the asynchronous synchronization
• 500 MIPS, 8 threads, XS1-L1 processor
• 2 Channel analog input
• 2 Channel analog output
  
• USB 2.0 high speed interface - supports multiple 24 bit, 192kHz channels with extremely low latency (3ms round trip)
• Plug-and-play with Audio Class 2.0 enabled computers (native Mac OSX support, Thesycon Windows drivers available)
• Audio Class 1.0 compliant - native Mac OSX and Windows support
• Asynchronous clocking - complete control of the audio master clock

Basically a USB to I2S converter. Optional support for SPDIF/ADAT/MIDI

DSD: XMOS supports the open DSD standard.

A beta is available.

Abbingdon Music Research - Digital Processor-777 €3.600

24/192kHz Asynchronous USB Audio Class 2.0 (XMOS)

Aesthetix Pandora DAC USD 5,000.-

• Card-based DAC with three digital input slots.
• AES/EBU, RCA Coax, Toslink standard on digital input 1 slot.
• USB standard on digital input 2 slot.
• USB capable of class 1 audio (96KHz, 24bit) and class 2 audio (192KHz, 24bit).
• 2nd USB input optional.
• Asynchronous USB, (Streamlength ™)
• DSP based digital section using Motorola DSP56362 for digital filters.
• DAC section based on Burr-Brown PCM1792A.
• Analog section featuring four vacuum tubes in differential configuration.
• Zero global feedback.
• Balanced and single-ended outputs.
• Volume control optional, allows DAC to drive a power amplifier directly. Switched resistor design.
• Remote control of all functions.
• Multiple stainless steel faraday cages isolate critical digital, analog and power supply sections.
• Two transformers, one for digital circuits and one for analog circuits.
• All aluminum chassis construction.
• RS232 control.
• 12v trigger.
• Unit Weight: 35 Lbs
• Dimensions: 18" width x 4 3/8" height x 18" depth

Anedio D2 DAC US$1470

Pre-amp / DAC with various digital inputs and headphone out.

Asynchronous USB using the XMOS receiver, Thesycon driver for Win.

Inputs:

USB: 24 bits, 44.1K, 48K, 88.2K, 96K, 176.4K, 192KHz
SPDIF 75-ohm BNC + RCA: 24 bits, 44.1K, 48K, 88.2K, 96K, 176.4K, 192KHz
SPDIF 75-ohm RCA: 24 bits, 44.1K, 48K, 88.2K, 96K, 176.4K, 192KHz
Tosllink Optical: 24 bits, 44.1K, 48K, 88.2K, 96KHz

Outputs:

RCA and XLR

Headphone

April Music Eximus DP1 US$ 2,295

DAC/Pre/Headphone amp

Digital Input:

1 USB 2.0 + driver for Win

USB receiver: XMOS

1 I2S 100 Ohms TTL Level,

2 SPDIF coax 75 Ohms,

1 AES/EBU, 110 Ohms,

1 Toslink

Analog Input: 1 RCA, 1 MINI JACK

Analog Output: 1 RCA, 1 XLR, 1 Headphone

Receiver: Cirris Logic C58416

ASRC: TI SRC4192 (can be bypassed)

DAC: TI PCM1794A

Arcam D33

Analogue Audio Output

• Conversion 2x Burr Brown 24-bit 192kHz Advanced Segment Delta-Sigma
• Signal to noise ratio > 110dB CCIR (unweighted)
• Harmonic distortion (1kHz) 0.0008% (20Hz — 20kHz, unweighted)
• Frequency response (+0.1dB, -0.5dB) 10Hz–20kHz
• Filtering User selectable, fast or slow roll-off
• Output level (0dB) 2.2Vrms
• Output impedance 47Ω
• Minimum load 5kΩ

Digital interfaces

• USB Class 1 electrically-isolated USB 1.1
• Class 2 USB 2.0 High Speed (480 Mbit/s)
• AES/EBU Up to 192kHz sample rate
• Coaxial S/PDIF x 2 Up to 192kHz sample rate
• Optical S/PDIF (TOSLINK) x 2 Up to 96kHz sample rate
Computer compatibility
• PC Windows 7, Vista & XP (driver required for 24/192 material)
• MAC OSX (no driver required)

Physical

• Dimensions W433 x D370 x H110mm
• Weight 6.2kg nett/10.0kg packed
• Power consumption 30W maximum
• Analogue output connection RCA Phono x 2, Balanced XLR x2

Remote control.

Price: £2000

ATOLL DAC200 €1500

Pre-amp with various digital inputs and headphone out

• 1 AES/EBU
• 2 SPDIF coaxi
• 3 SPDIF optical
• 1 USB : 24bits/192kHz (XMOS, driver for Win)
• 1 wireless dongle

Outputs:

• 1 coax
• 1 optical
• 1 RCA
• 1 XLR
• 1 headphone

DAC: BURR BROWN PCM1792 (24 bits/192 kHz)

Ayre QB-9 USD 2750.-

• Asynchronous USB (Streamlength ™)
• 16/24 bit/192 kHz.
• TheSycon USB Audio class 2 driver for Windows
• XMOS USB audio class 2 converter
• Minimum phase digital filter.
• Single-pass 16x oversampling.
• zero-feedback, fully-balanced discrete circuitry.
• Equilock circuitry for active gain devices.
• Ayre Conditioner (patent pending) power-line RFI filter.
• AyreLink communication system.

Frequency Response: DC - 20 kHz, ± 0.25 dB

Signal/Noise: 110 dB (unweighted)

Output Level: 4 volts balanced, 2 volts single-ended

The USB receiver section is isolated from the
rest of the audio circuitry with high-speed opto-isolators. This means that the RFI generated by the multitude of clocks operating inside the PC and its noise-generating switching power supply is completely kept out of one’s music system.

Ayre White paper

Bladelius USB DAC

• Accepts data up to 24 bit/192 kHz
• USB powered
• Asynchronous USB transfer, re-clocking with a fixed low jitter crystal clock
• Galvanic isolation between USB and the analog circuits,
• Super low noise power supply with multistage regulation and filtering
• For low out of band noise we use low order modulator
• Digital filter with minimum phase
• The analog output stage is a high performance stage with high drive capability
• Distortion < 0.001%
• Thd Noise -126db
• Output Level 2.5v @0db

B.M.C. DAC1 Pre HiRes USBII - € 3.248

DAC with preamp.

Asynchronous USB (24/192) with driver for Win.

Cambridge Audio DacMagic Plus £349.95

CYP AU-D160 £150.00

USB DAC with analogue out (RCA), headphone out and Toslink.

• Supports standard sampling rates - 44.1kHz, 48kHz, 88.2kHz, 96kHz, 192kHz
• Supports Bits : 16 Bits / 24Bits
• Power supplied by USB BUS Power
• The Headphone, R/L and Optical ports will simultaneously support audio output
• ASIO driver supported
• USB Audio Class 2.0 with asynchronus mode and driver for Win
• 500 MIPS, 8 threads, XS1-L1 processor (XMOS)

Digital & Analog Calyx DAC 24/192 - 1500.00 USD

D/A Converter IC ESS Technology ES9018 Sabre Reference 32-bit DAC

THD+N 0.0005% @ 1KHz, 0dBFS
SNR 125 dB, A-weighted, 2.2 Vrms
Channel Separation 140 dB @ 1KHz, 130 dB @ 20KHz

Digital Input Resolution and Sample Rate
USB : 24 bits / 44.1K, 48K, 88.2K, 96K, 176.4K, 192KHz
COAX : 32 bits / 44.1K, 48K, 88.2K, 96K, 176.4K, 192KHz

Line Output
Unbalanced stereo, RCA jacks with gold-plated contacts
Balanced stereo, XLR jacks with gold-plated contacts

Output Level 2.2 Vrms (unbalanced), 6.8 Vrms(balanced)
Output Offset 2 mV max

Comes with a ASIO driver for Win

It claims to do 24/192 on OSX without a driver so probably USB class 2 audio.

XMOS USB audio class 2 converter

Reviews

http://www.digitalaudioblog.com/2011/02/review-calyx-dac-24192.html

http://www.digital-highend.de/start/wp-content/bildupload/EN111_S.64-67.pdf

ExaSound E18 $2000

DAC with volume control and headphone out.

• ES9018 SABRE32 Reference DAC
• 8 channels at up to 32bit/384kHz (USB only)
• Asynchronous USB interface
• Ultra low jitter
• Galvanic isolation
• Bit-perfect ASIO Driver Reference-class specifications
• Automatic sampling rate switching
• Plays DXD 352.8 kHz

Firestone ILoveTW 299,00 EUR

DAC supporting both adaptive and asynchronous mode

Grace Design m903 € 1.545

Headphone amplifier, DAC, monitor controller

• Balanced and unbalanced analog inputs

• 24bit/192kHz digital stereo inputs- AES3, S/PDIF, TOSLINK and USB
  

• High speed asynchronous USB interface

• Driverless operation on Windows & Mac up to 96kHz/24bit
  

• Supports USB Class 2 audio specification for 192kHz/24bit operation on Windows & Mac (drivers needed for 192kHz operation under Windows)
  

iBasso D7 US$ 179

Portable USB DAC with volume control and headphone out.

- True 24Bit/192K USB-DAC, supports bit for bit decoding.
- Asynchronous USB transfer
- WM8740 DAC chip
- Up to 24Bit/192K coaxial output
- RCA output and Line out.
- Built-in +/- 5V class A headphone amplfier that run off of USB power
- Full aluminum case
- Measures 60W*93L*22H (mm), and weights 108g
- Comes with USB Cable, and Leather pouch

Lindemann USB-DAC 24/192 € 690,-

• Asynchronous USB interface (USB audio class 2 compatible) based on an XMOS-DSP with 500 Mips. Resolution up to 24 bits and 192 kHz. Three separate clocks for USB, 44.1 kHz (and multiples) and 48 kHz (and multiples).
• USB class 2 driver for Windows
• Digital interface controller (WM8805WM8805
  with efficient jitter reduction due to buffer storage and adaptive PLL. Guaranteed jitter level < 50 ps.
  
• High-precision master clock with < 2.5 ps timing jitter.
  
• DAC WM8742WM8742
  
• Minimum phase digital filter with apodizing behaviour.
  
• Fully-balanced, analog output stage (ADA4927ADA4927
  

Linnenberg udc 1 €1260.-

USB 2.0 compatible input

- Jitter free asynchronous data transfer (udc1 as master)

- Bit transparent drivers for Mac and PC operating systems

- Precision master 3ps crystal oscillator

- 24bit/192kHz Burr Brown digital - to - analogue converter

- True class A, fully discrete analogue circuits with zero negative feedback

- Ultra short signal path

- Balanced analogue outputs with PCB-mounted gold-plated Neutrik XLR sockets

- High current output stage

Specifications:

Frequency response 1Hz - 24kHz +0.1dB -0.5dB

Distortion and noise <0.01% 10Hz - 20kHz at -10dB

Output level 4V rms balanced

Output impedance 150 Ohms

Mains voltage 115V, 230V factory set

Dimensions (H x W x D) 55 x 165 x 224 mm

Meitner Audio MA-1 DAC $7,000

• XMOS USB 2.0 High Speed ​​Interface: 16, 24 bit
  sampling rate up to 192kHz
  Thesycon USB audio class 2 driver for Win
• Available Digital Inputs:
  • 1x USB
  • 1x AES/EBU (XLR)
  • 2x SPDIF (RCA)
  • 2x TOSLINK (Optical)
• Word lengths up to 24bit, and sample frequencies up to 192kHz are
  supported on all digital inputs.
• Analog Outputs:
  • Balanced (XLR)
  Output Line Level (0dBfs signal on AES/EBU input): 4.6Vrms
  Output Impedance: 300Ω
  • Un-Balanced (RCA)
  Output Line Level (0dBfs signal on AES/EBU input): 2.3Vrms
  Output Impedance: 150Ω

Musiland MD30 DAC/Headphone amp

• USB 2.0 High Speed ​​Interface: 16, 24, 32Bit sampling rate up to 192kHz
• Coaxial RCA, BNC coaxial, fiber optic, AES: 16, 24Bit sampling depth up to 192kHz. Support MMDI instruction
• MULINK high-definition digital interface (proprietary i2s): 16, 24, 32Bit sampling depth up to 192kHz. Support MMDI instruction.
• Clock jitter (44.1kHz): S/PDIF less than 30PS, USB, MULINK less than 20PS

Mytek Stereo192-DSD-DAC USD $1,695.00

• Asynchronous USB2 with driver (Rigisystems )up to 192 kHz
• Asynchronous Firewire 400/800 (TC Electronics)
• Conversion: 32bit, PCM up to 192k, 64xDSD, 128xDSD.
• Dynamic Range: 128dB (ESS Sabre chipset in 8 mono to 2 stereo config.) THD DAC: -110dB.
• Digital Audio Inputs: SPDIF, AES/EBU, Toslink all up to 192k single wire.
  (64xDSD and 128XDSD SDIF DSD interface on Mastering Version).
• Clock: Internal Clock Generator (10ps jitter), Wordclock In and Out, or sync to incoming digital audio input with low jitter JET (tm) PLL.
• Internal Async Hardware Upsampling- 16bit 44.1k etc. can be optionally upsampled prior to conversion to 192k/24bit with clock jitter eliminated.
• Transparent, 1dB stepped programmable analog attenuator, separate for main out and headphones.

Various models including one with headphone and pre-amp function.

A tread on a forum including Michal from Mytek.

Onkyo DAC-1000 £599.00

At the moment (January 2011) only available in Japan.

Peachtree Audio Grand Pre control center US$2995

DAC/preamp/headphone amp with volume control and defeatable tubed output.

Manufacturers description:

• Reference ESS Sabre32 DAC knocks jitter down to <1 picosecond for accurate sound reproduction
• Galvanic Isolation eliminates noise generated by switching power supplies in source components
• New asynchronous I2S 24/192 USB input provides the best connection between computer and DAC
• VCA gain control for minimal noise and cross talk replaces the commonly used potentiometer
• New Bascom King tube buffer rejuvenates poor recordings and compressed audio

Resonessence Labs Invicta $3.995 USD

• ESS SABRE32 24/192kHz DAC chip
• Digital filtering DSP and controls via Xilinx MicroBlaze FPGA soft processor cores
• Ultra-low phase noise oscillator master clock
• 1 x Toslink input and 1 x Toslink output
• 2 x BNC digital input
• 1 x AES/EBU input
• USB - asynchronous mode, high speed so probably USB audio class 2 compliant but no drivers for Windows available. USB firmware by Cypres Semiconductor.
• All digital inputs are transformer coupled, galvanically isolated
• 2 x headphone outputs on front panel, simultaneous drive and levels can be independently set
• SD card (WAV format only, up to 24/192)
• Low noise OLED screen
• Firmware upgradeable (FPGA)
• High quality AD797 J-FET operational amplifier output stage

The manual contains a lot of measurements.

Each measurement is accompanied by a short explanation, very instructive.

This DAC is linear up to 130 dB. An excellent values allowing for minimal full 22 bits resolution.

Rasteme Rudd14 56,700- Yen

24/192 asynchronous USB DAC.

USB receiver XMOS.

Teac UD-H01 DAC £299.00

Main Features

• USB Audio Class2 High-speed Input from PC/MAC (Tenor 8802)
• 32-bit/192kHz Dual D/A Convertors (BurrBrown 1795 x 2)
• Up-conversion to 32bit/192kHz
• Supports Asynchronous Transfer Mode
• Toroidal-core-Power Transformer
• Detachable AC Socket
• Headphone Out with Volume Control
• Aluminium Front Panel

General Specifications:

• USB Input: x 1 (USB2.0)
• Digital Audio Inputs: x 2 (Coaxial, Optical)
• Balanced Audio Output: x 1 (XLR, 1-GND, 2=Hot, 3=Cold)
• Audio Output: x 1 (RCA)
• Headphone Out: x 1 (6.3mm)
• Input Signal Sampling Rate: 44.1kHz, 48kHz, 88.2kHz, 96kHz, 176.4kHz, 192kHz
• Operation:230V AC, 50kHz
• Dimensions (W x H x D): 215mm x 55mm x 215mm

Wyred 4 Sound - DAC2 $1,499.00

• ESS Reference audio (ES9018) 32 bit DAC
• Automatic oversampling for precise output filtering
• Fully balanced design with balanced and unbalanced outputs
• Upgradable Digital, Output, and USB boards (designed for future improvements)
• VFD display for input, sample rate, volume control, and configuration viewing
• Remote control
• Defeatable - 32 bit volume control
• 2x Coax inputs
• 2x Toslink inputs
• 1x AES/EBU input
• 1x Balanced I2S input via HDMI cable (not standard HDMI cable format)
• 24-bit 192kHz Asynchronous USB input
• Proprietary drivers for 32/64 bit Windows XP, Vista, 7 and Mac OS 10.4, 10.5 ,10.6