Lehmann are a German manufacturer headed up by Norbert Lehmann and make a range of widely respected electronics.
A few years ago the idea of a headphone amplifier with a DAC were equally frowned upon, but as we become more involved in hi-res players and turn ‘antisocial’ using headphones as opposed to antisocially playing our loudspeakers too loud, this duo seems all the more relevant. There are certain duo’s that should always go together, like fish and chips and Marmite and cheese, and a few that probably shouldn’t like Audio Innovation’s CD player with built-in FM tuner. And, with the Lehmann Linear D being reviewed here, should you have friends to share with then there is an additional headphone socket so the two of you can listen together.
I just wish the on/off light at the front of the Linear D changed from blue to red to indicate a digital source, as you won’t see the blue light on the rear unless you turn off the room lights! This model is basically a single analogue input Linear with additional Toslink and S/PDIF RCA digital inputs. A blue light next to the sockets will indicate when a digital source is connected, with priority for the Toslink. The unit doesn’t need any manual switches to toggle between the analogue or digital sources, rather it recognises if a digital source is playing and switches across automatically, picking the optimal setting. The Sabre K2M DAC from ESS Technology on the quad-layer circuit board, which has been optimised against HF interference, can handle 24 bit digital inputs at sampling rates of 32 kHz; 44,1 kHz; 48 kHz; 88,2 kHz; 96 kHz; and 192 kHz. There is no provision for higher 384kHz or DSD conversion. The front of the unit is quite sparse with just the blue light to tell you when the unit is switched on, the all-important volume control, and two ¼ inch stereo Neutrik gold plated headphone sockets.
All sockets at the back are tightly packed at one end due to there being the on/off switch, IEC socket and fuse block at the other, and whilst there is labelling underneath the unit there is none at the rear itself which can be rather confusing if you are in a hurry to set up, particularly because the analogue left and right and digital RCA socket are not separated, which could be puzzling if you don’t read the manual or peek underneath the unit, and because where left and right analogue RCA inputs are set horizontally, the output left and right RCAs are vertically set on the right. I prefer in/out and left/right to be placed in rows, in the same way as they were in cassette and tape recorders, but old habits die hard. Two parallel outputs on the discrete class-A solid-state output stages powerfully feed two headphones connected in sockets at the front of the unit, preferably of equal impedance. For this test I used Sennheiser HD650’s (always difficult to drive well), Audio Technical W1000, Meze 99’s, and borrowed a pair of HD800’s.
Norbert Lehmann set up Lehmann Audio in Cologne, Germany, in 1988 when a young student of audio engineering, Since the Summer of 2007 he has been operating from Bergisch Gladbach. With a passion for detail of sound this German manufacturer has been producing a big selection of headphone amplifiers, phonostages and power amplifiers as skilfully as Britain’s very own Graham Slee. This product like many in his range is offered in a choice of matt aluminium, black or my favourite the shiny anodised aluminium. The Linear D also has vibration-absorbing SSC feet to “decouple the Linear D from its base and provide calmness”. Calmness was certainly manna from the power reserve in the zero global feedback Class A output stage that works well with any headphone, no matter what impedance. At £965.00 this is a medium price for a headphone amplifier, but bearing in mind the cost of decent headphones today it is proportionally only a small amount to pay for what for me was quite exceptional sound-per-pound. You get a headphone amplifier based on their very successful £649.95 Linear with added digital input, and one that is easy to operate once you get past connecting it up.
Kate Bush’s A Sky of Honey “Prologue” from her iconic ‘Aerial’ album gave an open and full-frequency performance delving into each individual instrument methodically and with great ease. Even the combined assortment of closing drums, piano and vocals were clearly defined in their own space, and the open C-chord from violins and piano ‘G’ in the centre stage isolated itself from an Ab “hum” that was well defined on the right ear, and continuing until the final fade. I hadn’t really noticed this before and I wonder if Kate also knew that it was there when she recorded the album in her home studio. The Lehmann gave excessive amount of detail without making it all sound confused or clinical. The sound was passionate, involving and musical. This was electrostatic detail with oomph.
Playing the Queen Symphony through the DAC, the piano-key pressing gave quick attacks that sounded good on the HD650. All instruments were clearly defined in their allotted space, and all sounds, whilst powerful and sumptuous, were still very sensitive to the detail. From the lowest sounds to the high glockenspiel I never got tired of listening. Berlioz Symphonie Fantastique (Robin Ticciati, Scottish Chamber Orchestra, Linn 24/192) was crystal clear, from the “brushing sounds” merged under the string introduction (which seems to be synonymous with a number of Linn recordings) to the brash brass bursts in the fourth movement. The dynamism of the music is allowed space in this headphone amp, and I felt more front-to-back awareness in the 2-dimentional HD650’s than I thought was possible. These are unflustered and clinical headphones at the worst of times, and this headphone amp played each individual note with a high degree of musicality and pizazz. The manual supplied shows how you can select the best output for your cans, with 2 micro-switches per channel situated under the unit allowing you to adjust amplification in a range of 0, +10, +18 and +20 dB, with the manual even listing suggestions for German headphones from companies including AKG, Beyer, Grado, Sennheiser and Ultrasone. Output gain was considered more important than matching impedances, and the unit worked well with both low and high impedances. Giving the HD650’s and HD800’s an extra 10dB of “welly” meant I was never short of power and the Linear lived up to its name with a very undeviating frequency response from lowest to highest. And, like the Black Cube Linear that I heard some years ago, the sound was full-bodied, rich and meaty, giving me masses of enjoyment.
Turning to mono with Ella and Louis “Can’t We Be Friends” (Ella Fitzgerald and Louis Armstrong) was defined and accurate, and with both of them singing the fact that this was a mono recording made it none the less enjoyable. Switching to the HD800’s and Audio Technica W1000 fifth generation headphones opened up the sound even more, becoming more human and enjoyable, especially the ‘muted’ trumpet solos. I didn’t really notice it was mono with the distant trumpet solos and piano contrasting with the closer vocal interjection. Prog rock album ‘Life within a Day’ track “Tall Ships” from Squacket (Chris Squire and Steve Hackett; YES and Genesis respectively) played with authority and detail, with clear decays from the bass drum that I could still hear clearly amongst all the other instruments still playing. Nothing was hidden. Indeed, in a later performance Pavlo Beznosiuk playing the Toccata and Fugue in A minor (JS Bach) on the solo violin rather than the organ illustrated further the space and decay of sounds. Back on Squackett, whilst I still prefer the original YES and Genesis, there are some great tracks on this second album from this duo. The Lehmann didn’t disguise some unadventurous mixing in this album, but kept it as I remember; particularly the very centralised mix-down in ‘Divided Self’. ‘Aliens’ was a very tame track and the Linear D made it all the more clear and not frightening with all the different short riffs fitting together that left me with a sea of smiles. Queen “One Vision” from A Kind of Magic (Queen Studio Collection, 2015) played with power and awe, with the bass particularly good on the Meze 99 Classic headphones, recently reviewed, and this MP3 download sounding surprisingly musical. The title track wasn’t flustered with its highly compressed drum beats. If anything the Lehmann opened up the sound so I didn’t get a headache. David Gilmour’s “5am” from ‘Rattle that Lock’ took me back to a restful state of mind. Pat Metheny Group ‘The Way Up’ opening track sounded clear and powerful with the ride cymbals in the percussion, guitars, synthesisers and Steve Reich’ inspired repeated phrases sounding crystal clear and refined. The HD650 relished this music, giving of itself as good as I have ever heard. Nothing rushed, all there and very detailed. Where I normally prefer my Audio Technicas, they now sounded too bright and the HD650 sounded more natural, and the HD800 just improved it one more degree.
The Linear D was surprisingly good choice for me to play with. Where I usually prefer tube headphone amps in order to get the musicality and personality in the sound, I felt very happy getting to know this product, both with analogue and digital sources. The sound was powerful, human, never flamboyant, but still sensitive to detail. It worked well with all I played, from classical, jazz, pop and folk. Having that extra 20dB of power up my sleeve was also good for those less efficient planar headphones that are flooding the market. I would therefore most certainly give this product a listen to if you are in the market for a headphone/DAC duo.