Усилители для наушников — Feliks Audio EUFORIA EVO

The Euforia Evo is a desktop OTL valve headphone amplifier and preamplifier from Feliks Audio of Poland. The maker describes it as its ultimate achievement in output transformerless design, and it is hand-assembled with components wired directly together, UPOCC internal cabling and selected parts. Compared with the earlier Euforia, the Evo adds an XLR headphone output, and its list price in the US is USD 3,349.

Key specs that matter

Each Euforia Evo ships with a matched pair of PsVane CV-181 Mk2 Gold driver tubes and a matched pair of 6N13S power tubes supplied as new old stock. Single ended output power reaches 280 mW, and gain is 20 dB. Input impedance is 100 kohm. The frequency response runs from 7 Hz to 80 kHz within 3 dB, measured into 300 ohm, and distortion is 0.4% into 300 ohm at 20 mW. Feliks Audio gives an optimal headphone impedance range of 32 to 600 ohm, planar magnetic models included. The chassis measures 31.3 x 20.3 x 19.3 cm and weighs 7 kg.

Engineering and use context

In an OTL circuit the power valves drive the headphones directly, without an output transformer between them and the load - here that role falls to the 6N13S pair, while the CV-181 valves handle the voltage gain ahead of them. The 6.3 mm headphone jack is joined by XLR and RCA headphone outputs, and the amplifier can also be used as a valve preamplifier ahead of a separate power stage. Versions for 230 V or 120 V mains are offered, the AC cable and a manual ship in the box, and the direct point to point wiring means the signal path runs without a printed circuit board between parts. Owners who keep the amplifier within reach of children or pets can order an optional cage that fits over the valves to protect them.

Pairing

With a stated range that starts at 32 ohm and covers most planar magnetic designs, the Euforia Evo can be matched with a wider choice of headphones than older OTL units designed only for high impedance loads, and it is also said to cope with low impedance loads below 32 ohm and with sensitive in-ear models, although high impedance dynamic models remain the load at which the maker quotes its figures. The source can be any DAC or streamer with an analog line output, and the fixed gain leaves ample reserve with high impedance headphones. For the in-ear case, the same fixed setting means most of the volume range is used near its lower end.

Alternatives

The Feliks Audio Echo Classic is the brand's entry level valve headphone amplifier, using 6N1P and 6N6P tubes and rated at 350 mW.