From the Decware website:
OVERVIEW:
The ZBOX is designed as a stand-alone tube output stage for CD players or DACs. After offering mods for a couple of different CD/DVD/SACD players that included a tube output stage, we decided to make the ZBOX so anyone could upgrade their CD player.
The ZBOX is not just another buffer stage, if it were it would only make things sound marginally better and only on certain players/DACs. The ZBOX works by creating a starved voltage condition in the filiment of the tube that in turn causes an increase in harmonics.
The results are as follows:
Restores proper frequency balance though better impedance matching.
Improves tone
Relaxes and openes up the music for better detail, imaging.
Reduces listener fatique.
Enhances the 3D effect of better recordings.
Of course there are no circuit boards and no Chinese parts. There is a lifetime warranty though. Internally the ZBOX uses top grade resistors and poly film & foil capacitors on each channel. The output level control is made by ALPS, internall wiring by MOGAMI. Voltages are low for tube gear so the tube lasts for many years. Because of the lower voltages and lack of heat the ZBOX is a plug in and forget item. Designed for 24/7 operation there is no power switch. This ensures that the unit is always warmed up and at peak performance any time you turn on your CD player.
A final advantage to using a ZBOX is the simple fact that you can tube roll with your choice of 12AX7's, 12AT7's or 12AU7's. Each of these tubes have a different signature as does every brand of each tube so you gain tremendous control over how your system sounds by voicing it to your tastes.
FEATURES:
The ZBOX features an RF proof powder coated steel chassis with removable power cord, one pair of input and one pair of output jacks and a level control. The tube is located so that it can be easily changed without removing any covers.
This is a plug it in and forget it solution to that CD sound that always errors towards thinness rather than richness. It removes the underlying stress in the playback of CD's that many people don't even realize is there until they've heard it gone.
SPECIFICATIONS:
This unit requires no adjustments or maintenance other than changing tube every few years. It is a self biasing design. Output tube life is several years.
Size
6"W x 11"D x 2.5" H
Weight
7 lbs
Chassis
Steel with black powder coat finish
Consumption
17 watts
Input jacks
Gold/Teflon RCA
Output jack
Gold/Teflon RCA
Input impedance
100,000 ohms
Output impedance
< 1000 ohms (aprox 300 ohms)
Frequency Response +/- 0.5dB
20Hz ~ 20kHz
Frequency Response +/- 1 dB
5Hz ~ 70kHz
Operating Voltage
120 VAC 50/60 cycles
Link to the Decware website (unit for sale looks exactly like the one on the website).
http://www.decware.com/newsite/zbox.htmPrice is $300 (PP and shipping fees apply)