Speaker amplifiers
Amplifiers chosen by the loudspeakers they will drive: eight single-ended tube models from 2 W to 30 W per channel, for sensitive full-range and three-way designs as well as larger floor-standing pairs, and two solid-state models with a built-in DAC, Bellerophon (from 25 W) and Hades (70 W as standard, up to 1 kW to order). The tube models have an 8 Ω output winding as standard, with 4 Ω or 16 Ω to order; every one is built to order.
The models
Demograf Audio
Solaria
2 W per channel: loudspeakers of about 98 dB and above, such as Orpheus at 103 dB, with a fast, hard-hitting bass.
from $27,800
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Demograf Audio
Eurybia
2 W per channel: loudspeakers from about 98 dB in a small or medium room, with tonal weight ahead of power.
from $26,600
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Demograf Audio
Tantal
3 W per channel: loudspeakers from about 96 dB, with voices and acoustic instruments placed precisely in space.
from $20,500
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Demograf Audio
Atlas
5 W per channel: loudspeakers from about 93 dB, such as Cassandra MkII at 95 dB; push-pull doubles the power.
from $24,200
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Demograf Audio
Helios MkII
15 W per channel: loudspeakers of about 90–93 dB, or more headroom with 93–97 dB models.
from $22,900
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Demograf Audio
Endymion
15–25 W per channel: loudspeakers from about 88 dB and larger rooms; push-pull for difficult loads.
from $36,200
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Demograf Audio
Ether
25 W per channel: loudspeakers from about 88 dB; a power supply of about 100 kg keeps the background black.
from $42,300
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Demograf Audio
Tantal Senior
30 W per channel: large rooms and loudspeakers from about 88 dB; two monoblocks as standard.
from $56,800
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Demograf Audio
Bellerophon
From 25 W, up to 150 W, in Class AB: stable into 4–16 Ω, with a DAC in the same chassis.
from $18,700
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Demograf Audio
Hades
70 W per channel, up to 1 kW to order: full-size loudspeakers, with a DAC in the same chassis.
from $14,500
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Matching the amplifier to your loudspeakers
With a single-ended tube amplifier, the loudspeaker’s sensitivity matters more than the watt figure. Every doubling of power adds 3 dB and ten times the power adds 10 dB, so the level at 1 m is roughly the sensitivity plus 10 × log10 of the power: Eurybia’s 2 W into 100 dB loudspeakers and Atlas’s 5 W into 95 dB loudspeakers both reach about 102–103 dB.
| Loudspeaker sensitivity (1 W / 1 m) | Models to consider |
|---|---|
| 98 dB and above | Solaria or Eurybia (2 W); Tantal (3 W) from about 96 dB |
| 93–97 dB | Atlas (5 W), or Helios MkII (15 W) for more headroom |
| 90–93 dB | Helios MkII (15 W) |
| From about 88 dB, or large rooms | Endymion (15–25 W), Ether (25 W) or Tantal Senior (30 W) |
| Any, into 4–16 Ω | Bellerophon (from 25 W) or Hades (70 W, up to 1 kW) |
A rule of thumb for a medium room of about 20–30 m² at normal listening levels; a push-pull build doubles the power of any tube model.
Who these amplifiers are for
For listeners who build the system around their loudspeakers. A sensitive full-range or three-way pair is filled with sound by a few watts of single-ended Class A, and the choice then turns on the voice of the tube: the 45, the 2A3, the 300B or the 3C24. A larger floor-standing pair, or a large room, needs the tens of watts of the transmitting triodes and the 4E27 pentodes.
Bellerophon and Hades suit listeners who want an amplifier and a DAC in one chassis, without tubes to replace.
Loudspeaker questions
Single-ended or push-pull?
Every tube model is built single-ended in pure Class A as standard. A push-pull build is available to order for less sensitive loudspeakers, larger rooms or more difficult loads; it doubles the output power. The topology is agreed with you before the build starts.
My loudspeakers are 4 Ω or 16 Ω. Is that a problem?
No. The tube models have an 8 Ω output transformer winding as standard, and a 4 Ω or 16 Ω winding is made to order, so tell us the nominal impedance of your loudspeakers. Bellerophon and Hades are stable into 4–16 Ω loads.
Can I connect headphones as well?
Yes. Every amplifier on this page also has a 6.3 mm and a 4-pin XLR headphone output beside its loudspeaker terminals. Headphone amplifiers describes the same models from the headphone side.
Tell us the sensitivity and impedance of your loudspeakers and the size of your room, and we will suggest the amplifier and its configuration.