New H20 Signature S250

After reaading a lot of reviews about these amps, i emailed Henry to build me (2) S250 to biamp my speakers, I have an immediate response from him and this is what he say:

Hi Patrick,

The Amps are the Signature Stereo which has an addional Big Toroidal
transfomrer which makes it a true dual mono design, for $300 more which
makes the amp now $2800. Of course, The amp is improved over the
regular stereo across the whole Audio Spectrum. If you want the regular
version stereo, let me know.

Thanks for the number and I'll try to give you a call sometime today.


Does anyone yet owned this amp?
I own the above amp. Words cannot describe my pleasure in owning this amp.

Mrcaspence1 did you purchase a Signature S250 or did you get the upgrade? I am curious as to the improvements over the standard S250. I currently have a S250 and am thinking of the upgrade, but would like to know what improvements to expect. I am using this amp to drive WATT 5.1's to great effect.

I just auditioned the sig S250 and it didn't like my Transparent Ref networked cables. Henry suggested this would happen to me, but I have long cable runs and couldn't easily find a good substitute cable without it getting real spendy.

My friend also auditioned one (he doesn't have networked cables) and placed an order. He's in love.

If anyone wants to donate 26 foot quality speaker cables, I'd place an order right away.
Woodburger, and all, if you can get past the price, which is $1600/pair, and think of them as world class digital amps, I'd suggest trying the Channel Islands Audio D100 monos (100wpc) designed by Dusty Vawter or the NuForce Reference 8 monos (100wpc) modified by Ric Shultz of EVS. Ric is a dealer for the NuForce amps, and sells them with his Level 1 mod included in the price. 30 day MBG. I heard the original 70wpc Reference 8 monos and thought they were incredibly clear, transparent and tight, but a touch sterile. Ric claims his mod corrects the sterility and makes them very musical. In fact, Ric gave up on the design of his own IcePower based amps when he heard the NuForce. I have a pair ordered.

Dusty Vawter's CI Audio D100 monos are tremenously musical amps. These also sell for $1600 direct from CI Audio. I presently have a pair of the D100 in my system.

I have been trying to find a low-cost replacement for my VAC Phi 110/110. I don't know yet if either of these digital amps will do it, since it's too early in the break-in process to judge, but I can say the 70wpc NuForce were amazing in their own right, and just three days out of the box, the D100 monos would be my choice over the Bryston 4B SST that I once owned.

Woodburger, I should add that I'm using 30 foot speaker cables, and neither amps have had a problem. The length of my cables was the primary reason for my post.

What problem did you have? I run MIT cables (that I love! - but not as much as my wife) and am curious what problems you had sonic wise.
It was odd. As if the mix of certain CDs (and not all of them) had been altered... some things were pushed farther into the mix. I had to turn it up to an uncomfortable point to retrieve them. I also thought (not really sure about this due to the fact I have a new room) that bass was emphasized.

I want to point out Henry Ho said that the network boxes would screw things up, and I believe he was right. He's a good guy with a good product at a great price.

I had three days listening with Anti-Cables after that, and thought they were much more harmonically correct than my Transparent Refs with the H20, but I couldn't fall in love for whatever reason - and it might have been listener's fatigue, to be honest with you and myself.

The H20 is a very very clean amp, IMHO, and if ever I can figure out how to listen to it on what I'd deem worthy wire without spending a fortune, I'd love to listen again. My goal was to get away from the tubes/retubing of my VT100 MKII - a great amp - just that I prefer the thought of no warm up, etc.

I search for a word - would have to say the VT is "cushioned" versus my brief run with the Anti-cables and H20 S250 sig... that combo was more dynamic and very very clean.
can the regular s-250 upgraded to the Signature 250?
Yes it can, Bob.
Woodburger, try the Goertz MI2 AlphaCore cables. They worked really well with the M250s I auditioned in my home. I believe you can buy them in lengths from AlphaCore and terminate them yourself without getting too spendy. I have owned MIT T2 and Analysis Plus 8 and ims the Goertz were far better. I have not tried them on a setup yet where they did not sound good.
I have the flat ones which are supposed to be better than the newer Boas.

My amp was purchased as a Signature S250.

I recently auditioned the Signature Stereo H20 in my system and liked it so much that I put an order in for one. Like Woodburger, I have an Audio Research VT100 MKII amp. I did not hear any of the problems that Woodburger reported in his system but I don't have networked cables either. Compared to my Audio Research VT100 tubed amp, the H20 is more dynamic with better controlled bass, more transparent, and drives my large ProAc speakers with more authority and slam. It also has a wonderful warm midrange and a smooth top end too. At the same time it gets the timbre and the harmonic neuances of acoustical instruments right and does this at least as well as my tubed amp which really suprised me. It does not sound in anyway like any of the Solid State amps that I have had in my system in the past. I never thought that I would ever get away from a tubed amp but the H20 has demonstrated that this is possible even for a tubeophile. The bottom line is that it really connects me to the music and that is why I am purchasing it.
Help! In reading back over all of the discussions and reviews on Henry's amplifiers, it appears that the best synergies have been found with tubed preamps. Is that true or am I just reading something into it that really isn't there? I've just ordered the S 250 sig. and discussed the same question briefly with Henry. I'm not really a tube lover, but prefer the more neutral sound of most good SS preamps. Having said that, I'm a bit concerned with the recent comments made in the 6 moons review relating to there "lack of texture." I realize that the reviewer is a confirmed tube lover and that may just have been his way of stating the obvious differences between tubes and SS. In any event, what used SS or tubed preamp in your opinion would best get me to where I want to go? My speakers are the Von Schweikert VR 4 HSE and I will most likely be using the Sim Audio Eclipse SE, as my source. Thanks in advance for your assistance.
Lloydf, my experience in using both a SS preamp and tube preamp with SS amps, a tube amp and digital switching amps is that the tube preamp adds a touch of three dimensionality and "life" to the presentation of SS and digital switching amps that is otherwise lacking. This is not an overwhelming change, but a change that can be heard, nonetheless.
Lloyd, You found the one seemingly ambiguous line in the whole review. The
writing went like this,

"Tubes create a certain texture which these amps don't. Tubes can be
very transparent but to my ears, it's a transparency modified in different
frequency bands and modulated by certain layering and soundstaging effects.
The latter are highly addictive ( consider me a major addict). But they are
effects. They simply do not ever arise in real life."

The H2O will not add any effects, good or bad, to the recording. It just excels
on digging out the deepest nuances of the recording. I find that much more

I believe a little bit of tubes is a good thing. My DAC has tubes. My preamp is
a class A solid state.
LLoydf, my comments above regarding my impression of the H20 signature were based on using an Audio Research Reference II tubed preamp.
I still think/suspect I just didn't have the right cables and that what made my interaction with the H2O not work for me at this time. I think it's a great amp anyway. Now that has to be some sort of odd statement. My tubes, in comparison, aren't as exciting.
Is anyone using these with electrostatic/Soundlab,Martin Logans,etc speakers? I must admit that I am being intriqued by all the buzz about these amps.I presently own a ARC-D150 power and I am on the fence big time.

I have run my Bel Canto evo4 on a friends Soundlab U2's and was not happy at all. The sound was immediately thin and bright'ish. Just no body and little emotion. Yet on my Magnepan 3.6's, the sound with the evo amplifier was outstanding.

The LC output filter in these digital amps don't sit particularly well with the transformer crossovers (with their associated wide variation in impedance) used in the Soundlab speakers. Also, Soundlabs and other electrostatics have very low inertia diaphrams and best performance, or that which is more critically damped, is ususally obtained with amplifiers featuring lower damping factors (a little output impedance). Just how much this really gives rise to the "thinness" is speculative though. Proper damping seems to have more effect on a systems musicality (or emotion). I think most of the perceived thin sound character is due to the LC output filter and the particular reactive crossover used in Soundlabs.

The Atmasphere OTL series works particularly well with Soundlabs. Other OTL amplifiers will likely also work well since some of their design philosophy is similar. Actually, tube amps in general with their relatively benign resistive plate impedance tend to mate well with Soundlabs.

Greetings all.
Since my last post, I've taken the plunge and had Henry build me an S250 signature. All I can say is, Boy am I glad I stumbled into this chat group. I'd have never found out about this wonderful product without it. Thanks all. Right out of the box, it sounded great to me and seems to be improving with each passing minute. Mine has been paired with both the Sim Audio P-5 and Conrad Johnson PR18 LS preamps, the Von Schweikert VR 4 HSE speakers and a Sim Audio Equinox CDP. Shifting preamps seems to make significant changes in the overall flavor of the system. The PR18LS is apparently voiced more like a tube preamp and has similar characteristics, while the P5 seemed more SS, more dynamic and less colored. This is definately a keeper. In closing, I'd like to mention that a local audio dealer stopped by during my demo. (He's trying to sell me one of the two preamps mentioned above.) I'd mentioned to him that I purchased Henry's amp. He wasn't too familar with any of the new D or T class amplifiers and wanted to hear one first hand. During his visit, he looked it over and comment on its fit and finish. He picked it up and commented that it must have some major transformers to weigh that much. He stood there listening to it for a minute and than said, "What did you pay for that again?" After I told him, he just shook his head and said, amazing. Again, thanks for all your comments and assistence.

How many hours do you have on your amp now? I ask because in my case (similar dynamic speaker load as yours) the amps seemed to take much longer to break in than those with more demanding loads (such as those driving Apogee's)...

I experienced significant improvement after the first 50-150 hours, and continued improvement well into 500 hours, and the last bit of the vocals becoming fully fleshed out and tube like was close to 800 hours if I recall correctly or so.

Keep us posted on how they evolve with time for you, please. I may be looking into a S250 for a secondary system in a few months... thank you for your input.
I've probably got less than 50 hours on my S250, so far. The Von Schweikert's aren't broken in yet either, so I was absolutely floored by how good the combination sounded right out of the box. I suspect that everything will improve with time. I'll keep you informed on my progress. I have one last question for you. I've had the First Sound Presence deluxe at the top of my Preamp wish list, but I'm not truly a tube lover. I much prefer the crystal clear more analytical sound and dynamics of most SS preamps. I've listened to a demo of the FSPD with my speakers, but not with this new applifier. In your opinion, how much would I be giving up going with the FSPD? I've asked you this question before, but in your travels, have you found a particular preamp that would get me closer to where I want to go? The Boulder preamp has the sound I like, but I can't afford it.(Atleast, not with a clear conscience.) I've read a recent 6 moons article on the Brazilian Audiopax Model 5 that sounds interesting, but the chat groups or other reviewers haven't given it much traction yet. I could order it blindly, but I hesitate to do something like that. Your thoughts would be appreciated.
Lloydf-Since your not looking for big name remote controlled preamps you might be interested in the Reflection Audio Quantum. Unfortunately there aren't many out there so the reviews are few if any. Don't let the battery power supply turn you off, it really works well.

The builder is a great guy and worth a phone call or an email to discuss what your looking for in a preamp.

My turn to jump in. I also have recently stumbled into finding out about the H20 amps. I have the Acoustic-Reality eAR II amp with the Jeff Rowland Synergy IIi preamp... driving a pair of DALI Helicon 400 speakers. (I can recommend the JR preamp with an ICE powered amp since it seems to have both SS and tube characteristics.) But after reading the discussion forums and the 6 Moons review, I contacted Henry (a very nice person to deal with I might add!) to inquire about getting the H2o Signature for audition. Apparently the shipping box for the audition unit has been trashed from all of the handling so Henry had to a new box to the person who is currently auditioning. I'm hoping to get the unit any day and can report on my findings. By the way, what is the warranty on Henry's amps and how long does it take to get one from when the order is placed? Thanks.
Welcome to the party, Grk. I came to H2O by way of the eAR II as well. H2O amps have a one year warranty, parts, or mechanical. From what I've heard, delivery can be made within two weeks. That's not Gospel.
Hi guys. The Signature upgrade is definitely worth it. I'm one of Henry's original "launch customers" and early last year purchased three of his S250s for tri-amping my Apogees. Well after a few months I started bugging Henry to try taking the S250 to the max..a signature version. After several months of phone calls and strategizing, he came up with stacked transformers, better caps, faster diodes, silver wiring plus other goodies. Right around X-mas, Henry said he was ready to give it a try so I sent my three amps back to act as guinea pigs. They had turned the 500-hour corner and were really opening up so I was a bit hesitant but boxed them up.

Boy am I glad I did! I'm at about the 1000-hour mark on these guys and they are definitely more open and transparent than the originals. The bass in particular is now very tight but bouncy and meaty too. I feel no need or desire to re-install my Tact amps and this is very high praise indeed. Excellent all the way around.

They DO need lots of break in. Henry actually sent me new amps as he really liked how the others sounded and wanted to use a couple of them as demos (which people keep wanting to buy!). Right out of the box I really didn't care for them but I knew better. I break amps in by running TV sound and cable fm thru them 24/7 so I can build up hours fast. After 100-150 hours their tonal balance settled in but the imaging was vague. At the 300-hour mark, things were much more organized but also still a bit "dark". The next time I listened to them seriously was at about 600 hours. Man what a difference! Very open & dynamic. And now at the 1000 hour mark they are superb and very artifact free with that sense of reality that the Tact amps have when driven via their digital inputs but with a DRIVE the Tacts don't have via the big Aps.

Like the Tact amps these guy really do benefit from being plugged into my PS Audio P-600 and then individually fed thru an ultimate outlet.

Perhaps tomorrow I'll get the chance to here one of them driving a friends big Sound Labs (currently being fed by the Parasound JC-1s). That should be interesting.


Feel free to drop me an email and I could give you more info on other preamps I have used as well, however - in a nutshell I think the First Sound Presence Deluxe Mk II would be the best of both worlds of the two preamps you have just auditioned. The First Sound Presence Deluxe Mk II is a tube preamp, however it does not sound like a tube preamp in the classic, tubey sense. The music emminates from a drop dead, quiet background, is rythmic, dynamic (both micro and macro), and has the drive that usually only SS preamps have. However, being tube, you also get the liquidity and texture of the instruments and vocals. Do a search in the forums here, as there is a thread running now over the past month or two on the FS PD MK II... Drop some NOS tubes into the preamp and this is a keeper.

I have paralleled your experience in trying many preamps in the past. Most were good, however excelled in one area and left you wanting for a bit more in another. This preamp will be staying in my system. If anything, I may splurge down the road and upgrade it to the 4.0

Again, feel free to email with any other questions. I am no expert, and have not tried hundreds of preamps out there, however it is difficult when there aren't local dealers to audition the gear you are trying to gain some insight into, thus I would be more than happy to offer any experiences I have had in comparisons.

You mate the right preamp with that combo and I think you will only need to worry about what music you will listen to next... :)
Let us know how they sound on the Soundlabs!

The CI Audio D100 monos have an anolog power supply. I'd be interested to know if anyone...especially the H2O groupies (and I mean that in the nicest way)...has heard the D100s. If so, how do they differ from the H20. How are they alike?
Thanks Muralmanl! One year doesn't seem like much, but I have not had any problems with my almost 2 year old eAR amp. I am looking forward to hearing what a beefy power supply can do to the ICE module. Grk.
Thanks for all your comments. The search continues.
The "250W" ice power module 250A is really a 150W (RMS) amplifier. Read the data sheet. Similarly, the '1000W' 1000ASP module can only sustain 85W of continuous operation at 25-degree-C, and 40W at 50-degree-C before thermal shut down occurs. Even without thermal shut down, 1000ASP can only provide 1000W for 15 seconds.

Also check out the phase shift: 250A at 20Khz is -30deg, 1000ASP is -70deg (maybe that's why they sound 'tube-like').
Extremephono, You are confusing H2O amp designation with B&O nomenclature. They are not interchangeable. All H2O amps employ the B&O 500 A module. They are all rated 250 watts into 8 ohms, and 500 watts into 4 ohms.

Henry Ho, the H2O designer, has chosen not to use the ASP modules, nor the 250 A module, because they don't meet his needs.
Well I took one of my S250 Sigs and a Tact S2150 over to my buddy Larry's place yesterday for a listen thru his, yet again, newly refurbished Sound Lab M-1s. The upgrades included a new membrane & stators (26 vs 20 per cell), new floor coupling structure and reworked/wired interface.

First off the M-1s are FABOULOUS. Period. This is one panel speaker that kicks ass dynamically with bass slamm like you read about. They don't need a sub. Nothing phases them. Peaks are scaled effortlessly and they don't just stop on a dime but can hit light speed before reaching the dimes edge. Larry's done a great job of setting them up too.

Front end was the latest Meitner DSD transport and DAC, followed by his two box tubed pre (forgot the name)all plugged into a PS Audio P300.

First listening thru the Parasound JC-1 all of the above characteristics were quite apparent. These are exceptional amps. The overall tonal balance, however, seemed a bit lean and forward to me with a slight nasal quality on certain material. I suspect there is a mild peak in the 1 Khz region. The soundstage was spectacular! A biiiiig panel that can image precisely. Wow!

Next we took my S250 Sig, plugged it into a PS Audio Ultimate Outlet which was them plugged into the P300. We used the single ended inputs with the Reference Line DSL cabling and Bybee filters that I brought with me. As the S250 had been sitting idle for about 4 hours and has a SERIOUS power supply (dual mono in fact with dual transformers)the in rush of power, promptly shut down the P300 which was already pushing 120 watts into the front end. After repowering everything back up there were no further power up problems as the S250s caps were now fully charged. At idle it drew only 20 watts.

The differences were immediately apparent and, to my ears and sonic priorities, better. Larry was a bit lukewarm at first as the amp needed some time to warm up sounding a bit constipated and dark until about 1/2 hours into the session. More serious was the fact that we just could not get the gain we needed to match our previous listening levels. The S250 has about 3-4 db less gain than the JC-1 and the single ended output of the pre drops the gain a further 6 db (we were using the pre's balanced output with the JC-1). So we had to listen thru the volume difference. What we did agree on was that everything was exceptionally CLEAN,open and detailed. That darkness was really the background blackness brought on by that cleanliness. Not so careful listening showed that there was actually more treble information but greater "liquidity". Though the volume was considerably lower, I though the overall presentation was less forward. Soundstaging was at first cramped but as the S250 warmed up it became huge, transparent and very well focused. A very musically involving presentation. However, we just could not really crank it so we tried the balanced inputs with his cables. Yup, much greater volume level but as this guy can deliver current, we shut down the P300 after only about another 3 db of volume. Rats! During that time however, it was pretty obvious to me that the balance inputs and their silver wiring needed breaking in with things sounding a bit thin and flat..but still pretty good.

To get around the input power limitations we then plugged the S250 into the conditioner that power the JC-1s (still using the balanced inputs). This is where things got interesting as yeah, there was more volume capability, but to my ears things took a good couple of steps backwards. Again, thinner and flatter. Then we tried plugging the Ultimate outlet into the chain. Wow! At first we thought things were darker again but not so, just cleaner. These things work for these type of amps and should be considered mandatory!!! I had noticed this effect before and much more dramatically with the Tact amps but was very pleasantly surprised to hear how much it did for the S250.

However, this does cloud a direct comparison of the S250 to the JC-1. As a system, I found the S250 (thru the well broken in single ended inputs), Ultimate Outlet, P300 combo superior to the JC-1. In fact, I think I preferred the S250 thru the balanced inputs and Ultimate outlet to the JC-1. Unfortunately, we did not have time to try the Ultimate outlet on the JC-1 or thru their never used, single ended inputs. My conclusion is that they will probably sound very similar to each other on an absolute basis. However the S250 Sig IS a whole lot cheaper and can, for an equivalent system price point, be taken up to a level that's noticeably superior to the JC-1 (IMHO) thru the use of an Ultimate outlet and Power Plant style device.

As this posting has gotten rather long winded, the bottom line is that the S250 Sig and the Soundlab M-1 are a great combination.

I'll save the long winded discourse concerning the Tact amp comparison for another posting but only say now that Larry like it and yes, they too can drive the big SLs.

I gather that the big selling point for the H2O amp is its analog power supply, capable of supplying lots of current for a long time. However, it is not obvious to me why this is important. Since we are powering a digital amp that has high efficiency the delivery of high amperage would be directly into the speaker, which would get fried! It would seem to me that a relatively small power supply with fast recovery would do the job just fine.

Tell me why this is incorrect.
There is one other, that I can think of, ICE amp with an analog power supply. That would be the bigger eAR amps. They have a relatively small one. All the other ICE amp builders use the digital ASP modules. Size counts. With the smaller analog supply, it doesn't exude body, like the H2O.

I have never heard of someone burning out a speaker with more than sufficient current.
Jeff: great "mini" review. I too, have had the pleasure of hearing Larry's system a couple times. Last time was prior to his Sound Lab "extreme make-over", so I can only imagine how good they sound now!

OK..., I have heard the H2o, and mostly agree it is quite an amp -- especially for the price (and also owned JC-1's for about a year), but has anyone seen, or more importantly heard, the Red Dragon ICE module amp? Listed here @ 'Gon for around $1700, and the guy's confident enought to let you audition for 45 DAYS, and wll pay the shipping BOTH WAYS. Interesting, eh?
Denf...When I made inquiry about the eAR amp I got an EMail from Red Dragon suggesting that I consider their unit. It appears to be virtually identical to the eAR 1000 watt amp, without the hassle of overseas shipment. Red Dragon is supposedly working on a multichannel version that I could configure for three channels, which is what I want.
Eldartford, like you, I believe the future of ICE and other digital amps lies in multi-channel applications. What a benefit to have crystal clear sound for 5,6 or 7 channels in an inexpensive and lightweight single box? Frankly, I'd be surprised if commercial theaters don't jump on this.

We two channel lovers will forever debate the attributes of digital vs. ss vs. tubes, but the multi-channel market seems to be wide open because listeners are less critical (no perjorative connotation intended). I mean how many viewers of "Die Hard" care about the "naturalness" of Bruce Willis' footfall on road gravel?
Tvad...You have a good point that digital amps make it possible to have half a dozen or so without dimming the lights or draining the bank account. Great for HT.

However, I am one who believes that, at least for music, every channel, amp and speaker, should be of the same high quality one would use for a 2-channel rig. When this is not done, which is often the case, audiophiles don't like multichannel. My "main" system is multichannel using the same stuff, eg: Maggie MG1.6, that I would use for a 2-channel system, but it has no video screen. Just a little 13" TV in the equipment rack for setup. In another room I have a plasma screen with a minimal multichannel audio rig (Panasonic SA-XR25 and inwall speakers) which is just fine for movies and TV.
Eldartford, I agree with you regarding the goal being the same level of quality between high end two channel amplification and high end multi-channel amplification. It's getting closer, and perhaps the gap has already closed and is just being discovered. The largest universe of audiophiles doesn't know the answer, but maybe a smaller subset does. From a marketing perspective, it makes more sense to me for the manufacturers of digital amplification to go after the HT crowd to establish a foothold.

I may have extrapolated too far when I read your comment that,"Red Dragon is supposedly working on a multichannel version that I could configure for three channels, which is what I want". I thought this meant you were after ICE amplification for HT application, but perhaps you meant multi-channel music application.
Hi All,

I too have taken the plunge on a Signature S250 this weekend and placed an order with Henry. All the dialog in this thread has been a compelling testament to give this amp a try.
Question I have is what preamp? Currently I run a Levinson 390S directly into my present amp and most recommendations indicate a good pre is required. I have a Proceed PRE sitting on the side that could be used but I gather that will just get me by until I can pick up something better. Requirements are the pre must be truly balanced, doesn't need to have lots of inputs as CD is my only source and must have a remote. I'd like price not to exceed the cost of the amp, if possible :>)

Before getting a preamp. I would try your 390s balanced direct into the H20. Its low output impedance output should mate very well.


The H20 also works well with low capacitance IC.

The H20 also works well with low capacitance IC.

Icepower does not recommend capacitive load > 470nF, or Quote Icepower data sheet: 'Higher capacitive loads may compromise stability and thus damage the device."
Mrcaspence1 - thanks for the info. My original intent was to use the 390S direct to the Sig S250. However, in another thread, I believe someone was going to use the AA player direct and was advised not to. Might work out provided the ICs are low capacitance.

You are welcome. You've got nothing to by lose trying it.

Warning to all who have an interest in hearing the H2O:

The H2O will spotlight any system deficiencies you probably were never aware of before.

For instance, occasionally we hear from MIT cable users complaining about harsh highs, and recessed mids they get from the H2O.

The H2O gets mixed into a lot of systems highly evolved along the intention of coaxing a favorable sound out of digital, and solid state. Some of those fixes severely interfere with the pure signal. They may change things for the positive in that system. The H2O, just doing what it does so well, will only magnify the actual wounds inflicted on the music by those "fixes."

The H2O will demand just as rigorous a search for the best system. It will encourage simple circuits, clean cabling, rich power sources, and revealing speakers.
I heard my H20 stereo unit in a highly evolved Tact system and the unit maintained its basic sound signature relative to other amps I heard in that system.

The preamp used is very important and should be of high quality as well as impedance compatible to hear the H20 at its best.

Well, if anyone has doubts about Henry and H2O Audio, I can say that my experience has been first class. Placed my order last weekend, amp arrived today. Removed my prior amp, placed the Signature S250 and listened. What an incredible improvement and I'm no where near the break-in that other folks have reached. Henry did burn it in for 2 days on his Apogee's. In my experience, it is like comparing an unbloomed rose to one in full bloom. The S250 is that rose in full bloom. It is letting so many more musical events through that have gone unheard. It is detailed, but not analytical, great PRAT, dynamics, wide soundstage and great imaging. I could go on and on....
But as always, YMMV.
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 piano’s 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.