Benchmark HPA4 vs Violectric V550 Pro

Both are desktop amplifiers, $3499 against $3600. This page puts them side by side on the only three things a maker can be held to — power, output impedance and noise — and then asks the question that actually matters: which headphones do they treat differently?

On raw power they are level: each reaches 100 dB on 567 of the 567 non-electrostatic models here.

A figure marked not published is missing from the maker’s own material, which is not the same as being good or bad. Where one of these two publishes a number and the other does not, the comparison on that axis cannot be made at all — and saying so is more useful than guessing.

Both makers publish a power rating, which is less common than the table above makes it look: of the 280 sources here, 209 publish a figure at at least one load and only 2 publish one at all four. Benchmark HPA4 publishes at 300 Ω; Violectric V550 Pro at 32 Ω, at 300 Ω and at 600 Ω. Every other row is worked out from those — between two published loads, or beyond them holding voltage constant, which understates rather than flatters.

So the two columns are not equally firm row by row: at 32 Ω and at 600 Ω only the Violectric V550 Pro figure is the maker’s own. On those rows the derived number is the one to doubt first.

What each of these labels means, and why a derived figure is still worth printing, is set out in how this data was built.

On power they are interchangeable across this whole database: there is no headphone here that one reaches 100 dB on and the other does not.

65 headphones stay below the audible-hiss threshold on the Benchmark HPA4 but cross it on the Violectric V550 Pro (64 Audio Nio, 64 Audio U12t, 64 Audio U18s, 62 more).

567 of the 567 models here reach 100 dB on both. That is a power count and nothing more; whether either source suits a given headphone also depends on the two lines above.

The counts above say how many models the two treat differently. This says by how much. The same 8 headphones appear on every page of this kind, ordered from the easiest to drive to the hardest, so a row can be read across pages as well as across columns. Headroom is at a 100 dB SPL peak.

The widest gap on the list is the Beyerdynamic DT 1990 Pro (250Ω): Violectric V550 Pro has +34 dB of headroom there against +29 dB. 5 dB is about 3.3 times the power, which matters for peaks rather than for how loud the music sits.

Hiss is this source’s own noise, in decibels SPL, in that headphone — not a rating. Below about 20 dB SPL it is under the threshold of hearing in a quiet room; a negative figure means it is far below it.

The Violectric V550 Pro costs $101 more than the Benchmark HPA4, and on these three axes the money buys nothing: among the 567 models here there is not one that the Violectric V550 Pro handles and the Benchmark HPA4 does not — not on power, not on the one-eighth rule, not on hiss. The traffic runs the other way: the cheaper Benchmark HPA4 keeps 65 models below the audible-hiss threshold that the Violectric V550 Pro does not.

Everything in this paragraph counts only figures the two makers published. An advantage on an axis one of them leaves blank cannot be counted, and is not counted — how often that happens is its own page.

Each has a page of its own with every power figure traced to what the maker published and a full headphone list: Benchmark HPA4 and Violectric V550 Pro. Or put either against your own headphones in the source comparison tool.