I just had the Pre 1 and the ZH 230 in my home this past weekend. I found both pieces to be exceptional. I use a mac mini feeding a Sonicweld Diverter HR which in turn feeds a Metrum Octave. My pre/amp combination consists of a Music Firs Audio Reference and a Graaf Modena amplifier or my Acoustic Reality Thaumaturge amps.
I am currently running the Modena. I tested the pre by running the Metrum Octave direct into the ZH230 and controlled via Pure Musics 64 bit volume control (dithering off (I am not a fan of dithered volume controls, i can hear the noise shaping effects)). This yields a very very pure sound and gives me a baseline to hear what other components in the chain (in this case the pre) are doing.
The Pre 1 did very little to the signal, it did in my opinion make the music a tad prettier. Nothing obtrusive or over the top, I just preferred listening with the Pre 1 as opposed to not having it in the chain.
Now comparing the Pre 1 to the MFA Reference, in my opinion was no contest with the MFA sounding more refined solid and simply in a different league. Now in all fairness, the Pre 1 is a $8.36k (w/o the phono, the one I auditioned had the phone and was $12.4k) while the MFA is $16k with no phono capability. The MFA had a more visceral and connected sound overall. The Pre 1 did sound better than my MFA Classic but that unit has less than 30 hours on it and is not in use i.e. it is sitting on a shelf waiting for other components to complete a 3rd system and has not been "juiced" in some time and it sounded like it when i put it in the system LOL. The classic usually takes about an hour to start to come up when it has been sitting dormant.
As far as active preamps go I would ratethe Pre 1 as one of the best I have heard.
The amp is very very very good and i may be picking one up. In comparison to the Graaf, I found almost the same results as the preamp comparison, I prefer the Graaf as it has more weight (gravitas) behind it. I would say the transparency of the two units is about equal but the ZH 230 does do something with the treble that is a little more exciting than the Graaf. It is as though the treble from the ZH230 is a bit more romantic but I am talking a very very very slight euphony, none of that rose colored crap :)
I think you could build a wonderful system around the 2 pieces and it would take quite a bit more money to equal or beat them.
For full disclosure I heard the ZH 230 on another occasion in my system with the stock setup i.e. high feedback (the way it comes from the factory) and stock tubes and I did not care for it. It had no weight to the sound no meat on the bones so to speak. It reminded me of most modern delta sigma dacs in that it had a sorta super transparent sound with seemingly little substance.
I talked to the sales guy about this and he said it was the feedback setting and to his credit he brought it the way it comes from the factory. I asked him on the follow up audition to set the feedback to what he thought was optimum. He did this and installed telefunken tubes (I believe they were telefunken) and that did the trick. The amp was now transformed and sounded wholly different with weight and body.
Overall I prefer my MFA and Graaf, but I will say these two pieces came pretty close. Another listener thought the Berning had a better bottom end than the Graaf, yet that claim was made when the Berning was playing a song that the Graaf did not play when in the chain, I can not agree with his finding.., but we all have our own way of hearing.
The next day I ran the Graaf in balanced mode and it exceeded what I had heard from it when run single ended in a way I would not have believed if someone had told me. I will not try to explain it because quite frankly it was so big a jump from single ended mode I think one would need to experience it.
I am glad I had a chance to hear the Berning gear in my home in my system and as I stated I may pick up the amp for my second system :)
Anyone who has read my comments should know that I write about what I heard and I am not interested in coloring my opinion because it may hurt someones feelings. This is a hobby and if more magazine reviewers would just be brutally honest I think a lot of us would waste a lot less money on crap products :)
Thanks