With the interest of a local audiophile who had an H20 (non-sig stereo) model on loan, I had the opportunity to audition this in my home system. As a Sound-Lab A1 owner with CAT JL-3 Signature amps and a 10-year old Counterpoint NPS400 hybrid amp, I was eager to hear how the H20 amp would compare to both a reference amp and a more affordable ($1500-2000 on the used market) amp. All amps were powered on for at least an hour before listening, and were only powered down for the brief periods of swapping IC and spkr cables and then powered back on.
There is much issue on MIT cables with the H20 amps in the Audiogon forums and from Mr. Ho when he wrote to me after my initial impression of his amp. But because I use a 25' MIT 350 EVO single-ended cable from an Aesthetix Callisto Signature line stage to the CAT amps, this cable was what I initially used to compare the amps. The CAT amps do not support balanced connections.
The H20 has outstanding extension and resolution at the frequency extremes. There was however, a huge dip in the midrange. On two different LP recordings, the singers, guitar and keyboard players were very much recessed on the stage relative to the other members of the band. I tried turning up the volume to bring the performers together, but this only caused the bass player and drummer to overpower the performance. In all the ARC, Counterpoint, Wolcott and CAT amps I have owned, my system has never had a tonal imbalance like this.
Another concern with the H20 had to do with image widths. Singers, guitar players and pianos all had a very narrow field. Piano image size was only a couple feet wide. The H20's image compression was very evident after hearing the same music minutes before with the CATs which brought the pianos presence to realism. The Counterpoint was not all that far behind the CATs in this regard.
The other problem with the H20 was its lack of dynamic contrasts. I could not get the loud peaks in the music to really come out into the room. With the CATs and less so with the Counterpoint, segments in the music would build up and briefly become quite loud and then return to a softer level. There was very much a defined volume range for which the H20 played the music and the brief loud peaks reached by the other amps were just not to be achieved with the H20.
The whole issue of decays and harmonic richness was not to be an expected strength here and indeed, the H20 was very much like any other solid state amp I have heard in my system and elsewhere.
Upon sharing my findings with Mr. Ho, he told me of the incompatibility with his amps and the MIT cables. With all the praise I have read here on these amps, I wanted to do anything I could to get out of them what others have written. The only option I had was to use a 14 NBS Statement XLR cable and run it across the room to hear this setup. This required me to bring the component rack a few feet into the room vs. being at the back wall, but the effort was well worth it. I used adaptors to run the NBS into the CATs.
Huge difference with the NBS balanced cable!!! Now the H20 had very good tonal coherency. Images were still a bit narrow, but a definite improvement here. I was very pleased with these changes.
The now far more accurate tonality brought on great musical enjoyment but at the same time, it made clear the subtle deficiencies that were masked before due to the recessed midrange. With piano now having more accurate presence, the notes were more clearly connected rather than being distinct from one to the next; intricate guitar work was a bit slurred from one note to the next as well. The Counterpoint did not fair very well here either, but with the CATs, the space between each of the notes was very clear. Without the CATs on hand to hear this capability, the H20's resolving power fairs quite well.
With the H20, there was still a definite reduction of each performer occupying a realistic volume of space on the stage. However, with the improvements brought on with the balanced NBS cable, overall, the result here was most impressive for an amp of this cost....and a solid state amp at that. Still this was one area where the Counterpoint clearly excelled over the H20. The 3-dimensionality, bloom, decays, etc., are very significant characterizations I listen for when evaluating audio components. To the H20's credit, it does have a more refined and resolving top-end than the Counterpoint.
The H20's dynamic compression issue with the single-ended MIT cable was now much less an issue with the balanced NBS. This was one area I was pleased to hear an improvement as I would have little tolerance for an amp of such dynamic compression.
One new problem with the balanced cable was that there was now a fatigue in the upper trebles. If anything, the NBS is more soft and a little less resolving on the top than the MIT, and yet there was now an annoying ringing in not the attack but the trailing (decay) of primarily percussion notes. I suspect this issue would make the H20 very system critical to find a balance elsewhere in the system to tame this characteristic. And perhaps this fatigue could be partly resolved with adjusting the Sound-Lab brilliance controls. Trying other cables could very well resolve this problem as well. Since I had this amp just for a couple days, I did not have the time to investigate these opportunities.
So what is the reason for the dramatic change between the two listening sessions? 1) is the H20 indeed incompatible with the MIT 350 EVO? OR 2) does the H20 simply need to be run with a balanced signal to achieve its potential? My gut feeling is the latter as the NBS and MIT cables used here have very subtle differences in my system and this has been true when I've run them with the Counterpoint as well as previously, the Wolcott monos. And the same was true when I had the BAT 31SE line stage before the Aesthetix Callisto.
I have found the line-stage-to-amp link to be by far the most critical of cable differences. And I have found only a few products capable of retaining the 3-dimensionality in the music; the NBS Statement and MIT 350 EVO & Reference Proline cables are among this group.
So yes, the H20 can perform incredibly well with the Sound-Lab speakers. When run with the "appropriate" cable(s) with the balanced inputs, this amp can be very impressive. The simple fact that it does not have listener fatigue, that I often associate with many solid state amps, speaks well for this amplifier. And that it faired so well to amps of the caliber of the CATs says a lot about the H20's potential and what I suspect exists to a higher degree in the Signature and mono amplifiers developed by Mr. Ho.
I hope to learn more from Mr. Ho on whether or not the H20 amp really needs to be driven by a balanced signal to work at its best.
John
