Mutec is a German company that primarily deals in the professional A/V sector, but they've recently started gaining traction with audiophiles. I picked up both options to check them out, and some of the wilder sections of the Internet have been raving about these interfaces. http://www.mutec-net.com/usbinterfaces.php Mutec MC-1.2 The MC-1.2 is a high-performance USB audio interface which converts from USB to AES3, AES3id and S/P-DIF signals, and vice versa. Uni- and bi-directional signal conversions Asynchronous USB operation USB audio stream isolation and conversion to 5 digital audio interfaces Low jitter audio clocks combined with ultra-low noise PCB design Regenerates and improves USB audio streams High-compatible USB audio class 2.0 driver for Windows supports ASIO, MME, DirectSound, WASAPI, Kernel Streaming, PCM 16Bit, 24Bit, 32Bit and Float-32Bit at all clock rates between 44.1kHz and 192.0kHz Individual lock indicators for USB and the digital audio inputs USB, AES/EBU, AES/EBUid and S/P-DIF interfaces in one box Status bit analysis for the S/P-DIF inputs S/P-DIF interconnections via BNC, RCA and optical interfaces Input sampling rate indicators, separated for USB and the digital audio inputs Bus-powered operation for mobile use Built-in, international power supply Available with aluminum- or black-colored front panel Compatible with Apple Macintosh and Windows PCs Mutec MC-3+ Smart Clock USB The MC-3+ Smart Clock USB is setting a new benchmark for clocking technology and the reproduction of digital audio by uniquely combining an audiophile USB interface with an audio re-clocker in perfection! Particularly designed for the demands of high-end consumer audio, the device expands a new sonic universe with increased musicality, clarity, and precision. As such, the MC-3+USB will prove its worth in many audiophile listening rooms around the world. Offers unique externally referenced re-clocking, locking to Rubidium-/Cesium atomic clocks or GPS receivers Audiophile, asynchronous two-channel USB interface with ultra-low noise audio clock oscillators and total galvanic isolation of up to 2500 VRMS, respectively 4242 VPK, for suppression of high-frequency interferences Converts DSD/DoP streams (64-256) to PCM audio with selectable output clock rate Locks to Rubidium- (10 MHz), Cesium- (5 MHz) and GPS clock references Improved, next-generation REVIVE re-clocking and 1G-Clock technology by MUTEC Additional Features: Serves as a flexible digital input switching matrix, audio format converter and master clock Compatible to Apple Macintosh and Windows PCs Intuitive user interface and easy installation Update-capability via USB Available with black- or clear aluminum front panel Galvanic isolation up to 2500 VRMS in accordance with UL1577, respectively 4242 VPK in accordance with DIN EN 60747-5-2 (VDE 0884 part 2) Converts DSD/DoP streams (64-256) to PCM audio with selectable output clock rate Transfers USB audio streams into AES3 and S/P-DIF and outputs those to five digital audio formats simultaneously Converts between USB PCM audio, USB DSD/DoP audio, AES3 and S/P-DIF, as well as between AES11 and Word Clock Highly compatible USB audio class 2.0 driver for Windows supporting ASIO, MME, DirectSound, WASAPI, Kernel Streaming, PCM 16Bit, 24Bit, 32Bit and Float-32Bit at all clock rates between 44.1kHzand 192.0kHz Ultra-low jitter Word Clock generation with clock rates up to 1,536.0 kHz Scalable to FS1x512 clock rates, 22,5792 MHz & 24,576 MHz, for e.g. high-end audio interfaces Locks to Rubidium- (10 MHz), Cesium- (5 MHz) and GPS clock references Generates Word Clocks, Super Clocks, AES3 + S/P-DIF blanks simultaneously Uninterruptable, fail-safe clock generation in all operation modes Eliminates so-called digital "clicks and pops" Individual lock indicators for the clock or audio reference and the re-clock reference USB, AES/EBU, AES/EBUid and S/P-DIF interfaces in one box S/P-DIF interconnections via BNC, RCA and optical interfaces available as in- and outputs Front panel lock-out for preventing of misuse Rack-space-saving 9.5" housing Built-in, universal power supply First Impressions I'll do detailed reviews of both units as soon as I am able to do so. Let me first say that The MC-1.2 is outstanding. I currently have an Audio-GD DI-U8 and CI Audio Transient MKII, It clearly bests the Audio-GD and, in my system, narrowly beats out the Transient MKII to my ears (note that I don't have the optional linear power supply for the Transient). The Mutec MC-1.2 isn't cheap at ~$460 street, but it's less than the CI Audio. It does nothing wrong, and provides a very clean BNC signal to my DACs (I also tried RCA). It can be powered by USB, but it's better to plug it into with a power cord unless you simply cannot do so. The MC-3+ Smart Clock USB has a street price of about $1030. At the price, it's actually more expensive than the MHDT Labs Atlantis DAC that I'm feeding a BNC signal. But I must say, this is the first USB interface I've ever used that I immediately thought, "Oh..." That thought can roughly translate to, "oh my gosh I'm actually sure I hear improvement." That lead to some A/B testing between the MC-3+ USB and the stock USB of my DAC. I was able to identify it blindly as my wife switched them every single time. "Crap," I thought. "I'm about to keep a USB -> S/P-DIF converter that costs more than my DAC." Further, I decided to buy a second MC-3+ Smart Clock USB. One for home, and one for work. Thankfully I overpaid on my taxes all year so I didn't destroy our entire bank account. Anyway, discuss! Peruse the various other forums that have been commenting on these in more detail. I'll update this thread as others engage and I spend more time with them. They are highly recommended.