I just installed my Zrock. I have two questions for those who already use this device.

First, my original intention was to install in between my pre-amp and UFO25. My pre-amp is a zero gain pre-amp from Denafrips so i did not anticipate any problems. However, in this position there was a very loud 'buzz' when in the active position. No buzz when the bypass was engaged. The output from the pre-amp is only 2.0Vrms. The only other variable might be that my DAC is connected to the pre-amp via XLR cables. Solving this problem takes me to my second questions.

I next installed the Zrock2 between my DAC (denafrips Pontus II) and my pre-amp. In this position the buzz was gone. However, when engaged at all but full position there is now a very noticeable drop in volume of at least 25%. Equally interesting, when i used the dial to set the level of the EQ the instructions suggested starting with the EQ fully engaged, then dialing back to increase volume to the maximum point (ie. as the highs become more engaged), and to stop when the volume starts reducing again. In my set up, volume was maximum when the EQ was fully engaged and only got quieter until I hit the noon position. The problem is, with the EQ fully engaged for reasonable volume, the sound is far far too bassy unless i have my amp set for very quiet listening. which means the ZROCK is only useful for extremely quiet listening, and not for beefing out the sound at regular volume.

Sigh. Anyone have any insights?

thanks Lon. I have tried the switch in the back in both positions. Same result, although the problem is worse in the down B position as it has a greater reduction in highs.

Hi Glenn,

Like you, I have my ZRock between my Pontus and my preamp. As you said, twisting the knob clockwise to about 5:00 would be too loud and too much bass. Going back to about 1:00 works best for me for bass, and then I add volume from either the preamp or amp.

I reread your post and cannot tell if, once you find your ZRock sweet spot, can't you then increase volume from the amp or preamp?

A brief update for anyone following this thread.

The volume drop off when theZROCK2 was in ahead of my pre amp had to do with my pre amp's impedance. Steve wrote: "The ZROCK is designed to go between your dac and preamp, however your preamp has an input impedance of 12K. That will create a large volume drop. We recommend 47K or higher."


I am now working my way through Decware support. Steve offered some suggestions and is sending a new tube in case it is a tube issue, failing which, i will send it back for repairs.

Two further observations. First Decware support has been great. Second, notwithstanding the buzz, when the Zrock2 feeds into my UFO25 Amp, and i don't have the volume issue i can really see its value and the improvement it makes to older music with poor bass.

I will keep you posted.

I thought i should report on the conclusion of my ZROCK2 buzz problem.

In case you are new to this thread, i purchased a Zrock2 - but found it had a prominent buzz of +5db when my 25th anniversary amp is dialed past 1oclock in volume. This means it is good for boosting bass for low volume listening, but not for 'fixing' low bass records (say early Motown) when played at a higher volume.  

I sent the unit back to Decware. Steve was unable to detect any problems with the unit. After listening to the recording i provided he agreed there is a buzz and concluded it must be entering the unit via a connector. I decided to have the unit returned to me, notwithstanding the buzz, as it still work well to improve bass, etc. at lower volumes.

After reinstalling the unit, i checked my interconnects carefully. (I use Decware Silver Reference interconnects through out my system). I also made sure they do lie across my power cable,. Buzz is still there.

So - i have decided to live with the problem and limitations. If anyone else has experienced and solved a buzz in their Zrock2 - please let me know.

Mine went away plugged in at another location, I reinstalled with an isolation transformer and there are no issues, but I made more than one change so this is anecdotal at best...

You can email decwarecustomercare@gmail.com if you continue to have problems.