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A. Low level information? Correct, but no soft clipping and/or tube compression. The Mosfet I use is nothing esoteric. It is all achieved with the circuit topology and design. The Fire is a very unique design. 1/ Idle current is more like a power amp and yes the Fire can be considered a small power amp. It can do about 8 watts cleanly and directly drive the speakers. Though I don't have anything here that is suitably efficient, efficient horns with 100dB+ efficiency will be driven to great effect and may in fact turn out to be nirvana. The gain needs to be turned up a bit however. High idle current naturally achieves linearity. To show off that it can drive speakers directly was not the design goal. It is just a side effect of the design choices I made that it can. 2/ Direct coupling. There are no capacitors in the signal path anywhere. 3/ More unique is that the entire circuit has none of the usual lead/lag capacitor compensation. This I hate most and won’t use if I don't have to. I found that bandwidth-robbing capacitors never sound as pristine in a circuit than one without them if everything else is equal. 4/ Last but certainly not least is being single ended and extremely simple and straightforward.

Q. The H2O amps utilize old-school linear power supplies. Why no SMPS?

A. Switching supplies spit out lots of garbage though I think B&O did an outstanding job minimizing theirs but still, I’d rather it not be there than having to tame it. Besides that in my experience the traditional supply just sounds much better. As for current delivery I feel that subjectively the analog design sounds just right across the spectrum and can deliver much more low bass.

Q. With the popularity of your class A designs, why the switch to D? And why ICEpower in particular?

A. Class D sounds great. Really, I just found the midrange liquidity unique and almost impossible to find in solid-state designs. And of course that came along with all the other bonuses, the ability to deal with tough loads, efficiency and all that. I found ICEpower to be the best so far.

The amplifier and preamplifier
arrived in three industrial cardboard boxes, the heaviest containing the amplifier with two nylon rope handles for easier handling. The components were protected by every imaginable grade and style of foam from medium-density cut pieces to packages of expanded foam as well as bubble wrap and larger air pouches. A remote was included as well as a pair of umbilicals for the twin-chassis preamplifier. A standard power cord does not ship with either unit because Mr. Ho regards a quality aftermarket power cable to be the norm for prospective buyers.

The chassis of the S250 Signature is thick aluminum plate, the face having the company name and model name carved deep into the surface. By digital amplifier standards this one is relatively heavy and reasonably large, measuring approximately 13.5” x 14.5” x 6” due to a traditional linear power supply. Fasteners on both amplifier and preamp are Allen screws. The amplifier accepts both XLR and RCA inputs with a small switching toggle. The RCAs are by Vampire, the biwire binding post by Cardas. The mains rocker is on the rear because the amplifier is intended to be left on 24/7.

The Fire preamplifier is a two-box affair, one box for amplification and input switching, the other an overbuilt power supply whose weight and size are the result of two large toroids. This eschews the aluminum panels of the S250 Signature for more conventional sheet metal with thick aluminum faceplate. The H2O logo and Fire/Firepower designations are painted bright red to mismatch the amplifier. The two boxes connect via a pair of 58-inch locking umbilicals. The main unit measures 14 x 10.5 x 6.5” and the power supply is 14.5 x 13.5 x 4.5”.  The designer prefers that the Fire not be stacked atop its power supply.

Connectivity of the single-ended Fire consists of 4 inputs and two outputs, all connectors by Cardas. An additional computer multi-pin port is earmarked for future consideration. The Firepower has a rear-mounted rocker mains. Layout and accessibility are straightforward and intuitive, with a few minor eccentricities reserved for the remote. Functionality is Spartan, with only volume control and source selection on the front panel. Volume is controlled via motorized conductive plastic Alps pot either from the front or remote. Source selection is via rotary switch not duplicated on the remote. Visual source confirmation is by one of four blue LEDs.  The nondescript remote shows no company logo and offers four bubble-style buttons numbered 1 through 4 in a lightweight plastic shell. Volume is raised by pressing 1, lowered by pressing 2. Depressing the third button activates and deactivates a muting relay.  A blue LED beside the front panel source selector lights up when mute is disengaged. The mute function is accessible only via the wand. Should you encounter difficulties with the remote, this eccentricity could render operation problematic if you’re somehow stuck in mute.  Mr. Ho has assured me that this will be addressed with a toggle switch in future production. The 4th button currently serves no purpose.

Aesthetically the amplifier is reassuringly solid, unobtrusive and plain in basic black. The Fire preamplifier too lacks the sculpted sophistication of rivals but compensates with solid heft. These components are designed to be heard, not ogled. Mr. Ho sent a useful list of precautions to adhere to: Do not connect the DC cable which ties the Firepower supply to the Fire whilst the former is on. You want to make sure both are connected before applying power. Though both DC cables are identical, they must not be crossed or remote and switching will be disabled and the outputs muted. After applying power there is a turn-on delay. Wait for 5 minutes then hit 3 on the remote to see a blue LED come on. On the amplifier the outputs cannot be shorted even momentarily or irreversible damage will result.

The audition proceeded in different rounds to establish compatibility with other components, cable interactions and by addition and subtraction distill the character of the individual components. Initial listening was on the Apogee Duetta Signatures running full range. First up was the pairing of Densen 130+ preamplifier stage with the S250 to establish how much inherent dynamic character would survive the transition to a wholly different amplifier design. Next came the AudioSpace Reference 2S preamp to examine a tubular frame of mind followed by the company’s Fire. The amp then made room for the Bel Canto 200.4 and Fire combo. As final evaluation the S250 Signature and Fire were re-teamed driving the AudioSpace AS3/5A monitors with Paradigm subwoofer. This allowed me to see how much virtue remained when the amplifier was robbed of strutting its disconcerting bass muscle. Cables were interchanged to check for affinities.

There was considerable change in sound over the course of break in. The S250 Signature amplifier started out powerful in the bass but quite dark overall. As time progressed the unit became progressively more transparent and extended in the upper frequencies. The Fire preamplifier was diametrically opposed, initially exhibiting a substantial peak in the upper midrange which mellowed over the course of the review and blossomed into an overall character which was extended and powerful in the lower ranges and smoother in the higher frequencies. The only functional anomaly I encountered was on the preamp. The lowest volume setting did not produce mute but leaked some output which required the use of the mute control to fully silence.