Legacy Audio i.V4 Ultra multi-channel amplifier Review

I am not alone

Rarely do I get indirect confirmation of evaluation of a component and conclusions reached in regard to industry trends from a different HiFi publication’s review, but it happened in this instance. I do not care greatly what other reviewers say in regards to equipment; I prefer to reach my own conclusions based on my impressions from attending shows, discussions with manufacturers, and handling products. I have a busy reviewing calendar and have little time to dedicate to following reviews from any source. I am usually through The Absolute Sound or Stereophile in less than 60 minutes, and I typically pay more attention to the ads for new products than the articles. I am unwilling to cut into my listening and reviewing to delve more deeply. I treat other reviewers the way I treat viewing professional sports; it’s nice occasionally to watch, but I would rather be involved in activity than watch someone else play. Once in a great while there is a review worth a closer look.

In the article I am about to reference, the larger implications in regard to the industry are more important to me than the discussion of the amplifier under review. I refer to the February 2021 issue of The Absolute Sound and Jacob Heilbrunn’s review of the PS Audio Stellar M1200 amplifier (I do not recall meeting him, have no personal intent associated with my comments, and have not been in communication with PS Audio). It is a hybrid mono amp using the ICEpower mono module (1200AS1), versus the stereo module (1200AS2) used in the i.V4 Ultra. The designation M1200 is not to be construed as indicating 1200 Watts into 8 Ohms; its output into 4 Ohms is 1200Wpc. The output of the i.V4 Ultra is 1000Wpc for up to four channels. Into 8 Ohms the PS Audio amp outputs 600Wpc, and the Legacy amp outputs 610Wpc.

Paul Meister, Sales Manager at ICEpower America, pointed out that the performance of these modules should be nearly identical. In case any technically oriented listeners wondered about the potential for crosstalk in the bridged stereo module used in the i.V4 Ultra, Paul shared with me, “There is potential for more crosstalk in a multichannel design, but thanks to the dual fixed bridge mono outputs, an inherently low idle noise level and other engineering techniques, the crosstalk between the two channels is extremely low, especially for the given power output.” The selection of the same model of module in either stereo or mono form should not be a determinant of an amp’s overall performance in this situation.

Bill discusses the topology of each channel’s design as follows:

“All amplifier channels in the iV series are differential bridge designs. Such designs provide much greater voltage and require higher current power supplies to support it.  The inputs to each channel are balanced as necessary. 

The iV4 Ultra dedicates the entire power supply of an 1200AS2 to supply the exceptionally high current capability.  The chassis design is unusual as each chassis component has the anodized coating polished away at mating junctions to provide a continuous electromechanical cage. The custom fabricated mounting aluminum bracket greatly increases heat sinking.  Each module’s heat sink has an individual grounding lead running directly back to the inputs. 

The iV Ultra Monobloc adds a high purity copper bar weighing in a 6 pounds to further refine the grounding scheme.”

I consider tubes to be dirty, outdated technology in comparison to what is happening with class D. One of the strong conclusions I reach in this article is that I am pretty much done with tubes. I see no compelling reason to subject myself to such comparatively unstable and noisy parts. This judgment will no doubt incur much wrath, but please keep your vigilante attitude in check until you have heard the likes of the i.V Ultra design. I also must hold my assessment tentatively until such time that I might work with a class D amp with a tube, like the Stellar M1200. Do I have a great desire to do so? No, not really, but if I am to prevent anchoring to a preconception, I have to push myself to explore beyond what I think is correct. Perceptions can be quite strong, but wrong. I remain open to the possibility that a class D design with a tube might be surprising. This is all peripheral; the takeaway from this discussion is that both Heilbrunn and I are quite impressed by the global performance of these ICEpower-based designs. In other words, multiple component makers are utilizing new modules to create stunning class D amplifiers.

This armchair assessment of the two amps apart from an actual comparison is soft reviewing, and as expected will be debated by others who will offer their armchair opinions. There is an aspect of Heilbrunn’s review that I consider more important, and it is revealed in his subtle comments, such as when he drives the Wilson WAMM speakers and reports, “The M1200 is not a good amplifier; it is a superb one.” How many $50K+ amps, mono or stereo, has this man used in his system, and he is enthusing about an affordably priced Class D as superb? I get it, because I am hearing the sibling ICEpower module in the i.V4 Ultra, which employs the same ICEedge technology.

As I read it, he softens the implication of the Stellar M1200’s performance, the pertinent phrases being, “The M1200 poses a real challenge for much of the audio industry… upends many old verities of switching amplification.” I will be more direct; the makers of class A, A/B and tube amps are in serious trouble. They are going to be routed by class D, and sooner rather than later. The i.V4 Ultra is already superior in every parameter of sound quality among the amps I have used. It is impossible to tell whether the M1200 has some softness, which calls for a slightly moderate devaluation, or whether Jacob is softening the message for the sake of manufacturers of other genres of amps. It could be counter-productive to accessing amps for reviewing if one dismisses them, a thought I have considered seriously as I write this article. Weighing anchor entails leaving something behind, and I am ready to do so.

A tidal change is coming, and it will break with ferocious power upon the landscape of traditional HiFi amp manufacturers! Many will not survive because they did not pivot and take up the class D cause in time. Eventually there will be myriad cast-off tube and SS amps for the picking by budget audiophiles, but those who have moved to a better expression of SOTA will consider them second rate. The value of such used amps will drop precipitously, and owners will be appalled at the pitiful selling prices. The damage will be attributable to the ascendancy of class D. For twenty years it has been moving, developing, and now a catastrophic event is underway in the amplifier sector.

Too dramatic, you say? Completely out of touch with reality? Perhaps, but those who know my writing know I do not play games with performance. I do not hold equipment to use in reviews for appearances. I could seek to pad my ancillary components with high profile products, but I refuse to do so if they are outperformed. This leads to a bombshell: The i.V4 Ultra outperforms even the 157-pound, $42K Pass Labs XA200.8 Mono Block Amplifiers that I lauded only months ago at 30 pounds (heavy for class D).

This is not a hit job on Pass Laboratories but on all other classes of amps! Actually, not a hit, but an announcement of a memorial service. These others are dying, and I have attempted to warn some more than once. I personally discussed with Nelson the urgency of moving into class D, telling him that I know of no other designer that could do justice, who would be so capable of exploring that genre of amplification. Nelson is an eminently polite man, and was very considerate as he brushed aside my recommendation.

Meanwhile, those who have endured the jousting on a particular thread about class D amps at an online community have seen the announcement by participant “Atma-sphere” that his company is working diligently on a class D amp, and has received a patent that he feels is a breakthrough. Atma-sphere is positioning itself to survive the tsunami. Likely, Pass Labs will also come through intact, because of its sheer clout, global presence and the fierceness of adherents to class A and A/B. It will be heartbreaking, devastating to the small manufacturers. As class D draws away thousands of customers, these companies will implode. Increasingly, audiophiles will refuse to pay big dollars and haul heavy amps of any class that simple comparison to current class D demonstrates cannot compete. Do not discount the i.V4 Ultra as an HT multi-channel value play, or think I am skewing the perception of performance to accommodate a favorable outcome for class D. I am giving a hard performance assessment of this amplifier, and drawing conclusions based on it.

There will also be winners, even new companies, to emerge with the class D trend. As more designers and manufacturers jump onboard the good ship class D, it will sail ever more proudly. The gap will continue to widen until, with wholesale abandonment of these others, save the hardest of hard-core nostalgia users, ridiculously priced (relative to performance) boutique amp makers, and bottom feeders picking up the pieces of company remains, class D will emerge as the undeniable victor, the premier amplifier genre. I expect these others to go to war over this, because this is business and people’s livelihoods. That is why I have attempted to give fair warning. The playing field is not level, but neither is it impossible for more traditional amp makers to participate, given that companies like ICEpower make OEM modules available. If not for that, it truly would become a bloodbath in the amp sector.

In terms of system building, however, it is already too late for these other classes of amps. I had the bulk of these comments, including the revelation of the return of the XA200.8 monos, in my notes for use in this article before I saw Heilbrunn’s review. Discovery of the review of the Stellar M1200 was independent confirmation of my assessment. I may be premature in my predictions, but I am confident that I see how things roughly will play out. I am already shifting; in terms of review planning, I am going to pull away from those other classes. Tube amps are simply too dirty and fraught with idiosyncrasies, and class A and A/B is showing to be old and rehashed technology, with few major tricks up its sleeve. I have not handled the uber-amps, ones in the $100K+ range, and perhaps for now they are safe — for now. That, however, impacts a scant percentage of the marketplace, which may ultimately be the only sector of such amps apart from class D to survive. Frankly, longer term I do not see redeeming technology on the horizon to save those genres of amps.

If this particular class D amp has bested all the tube and SS amps I have used in 14 years— and ICEpower is only one class D horse in the race—I conclude the amplification race belongs to class D. Having said this, I reserve the right to conduct a comparison to what I feel is an unusually worthy contender from a different genre, but I think I’m done with the bulk of tube and other SS amps.