Conclusion editor:

An amazing value! Unique tube-based clock. At its best, with the board upgrade, the Eight closes in on even the most expensive competition. It’s blessed with plenty of boogie factor, superb clarity, sensuous mids, and lovely harmonic bloom. Its portrayal of the soundstage is wonderfully transparent.

Out of the box, upper octaves are a bit grainy and bright. Tube dampers significantly help , as do vintage preamp tubes. DO, 183

Information from the website

Revolutions are born in bold ideas. In true PrimaLuna fashion, the stunning ProLogue CD Player will revolutionize the audio industry by introducing the world’s first tube-based data clocking device: the SuperTubeClock™

By incorporating a low-noise mini-triode vacuum tube into the digital clock, this boldly conceived design provides vastly superior resolution, detail retrieval, improved clarity, increased definition and detail from top to bottom.

The ProLogue CD player is a true dual-mono design, right down to the dual vacuum tube rectification — another first in a CD player. The power supply is adapted from the award winning ProLogue Three preamp, as are its high quality resistors, mosfets, and Solen capacitors which yield superior transient response, detail, and channel separation. The ProLogue CD Player comes equipped with:

• TRUE DUAL MONO OUTPUT STAGE Using one 12AX7 and one 12AU7 per channel.
• VACUUM TUBE RECTIFIED POWER SUPPLY Adapted from the award-winning ProLogue Three preamp that incorporates eleven separate power supply regulation circuits.
• STATE-OF-THE-ART Utilizing Burr Brown SRC4192 24bit/192kHz upsampling circuit with accompanying Burr Brown PCM1792 DACs.
• THE SUPERTUBECLOCK™ An ultra-low jitter clocking device that replaces the solid-state oscillator with a vacuum tube. Yields incredible detail retrieval and dynamics throughout the entire audio spectrum.
• SUPER I/V BOARD The Super IV board incorporates a new type of op-amp that to our knowledge has never been used by any audio manufacturer before. The Super I/V Board also upgrades the bypass caps and power supply caps, so with the increase of speed, detail, and quietness you get above, you get a prettier “picture.”
• PREMIUM PARTS Including polypropylene coupling caps, triple pi power supply filters, custom designed isolation transformers separating the analog and digital devices, resulting in decreased signal degradation and improved sonics from top to bottom.
• True Dual Mono output stage using one 12AX7 and one 12AU7 per channel.
• Beautiful heavy-gauge anodized brushed aluminum remote control. Controls all important CD operations and will even control functions on the DiaLogue components. Comes with rubber rings on both ends to protect furniture.
• Chassis made of finely finished heavy gauge steel, and five step automotive quality finish. Each coat hand rubbed and polished. Removable tube cage included no charge.
• Conservative design runs tubes easy for long life.