Hardware Reviews

CAAS Audio Elysian Pre-amplifier II, Elysian 100 Mono-blocks

E100s x 2 EPre v4 547

Built by brothers Carl and Neil Broomfield in Yorkshire the CAAS Audio electronics are pretty ambitious bits of kit by British standards. There aren’t many small companies making components with casework that’s milled from a single aluminium billet in these isles and even fewer who have developed their own amplification and volume control circuits.

CAAS stands for Class A Audio Systems and that is the operational mode chosen for the latest addition to the range, the Elysian Pre-amplifier II, this is the current pinnacle of the company’s technological achievement and as you can see, heavily biased toward balanced operation. It does have a couple of single ended RCA inputs but they are there for the source components that have nothing else, the Elysian amplifiers are all about maintaining a balanced signal from input to output. A message I eventually managed to pick up.


The latest version of this preamplifier differs from its identically cased predecessor by virtue of a “new fully balanced, ultra low distortion, zero feedback, dual monaural BJT amplifier stage”. I spoke to Carl about this change and discovered that while the JFET’s in the first EPre had a very high input impedance, which is good for the ladder resistor volume control, and very good measurements for both dynamic and static distortion, the BJTs (bi-polar junction transistors) that have replaced them have lower distortion and, crucially, sound better.

The ladder resistor volume control is a critical part of the EPre, it uses a bank of silver contact relays and metal film resistors to offer an attenuation range of 64dB in half decibel steps. In the first EPre this range was geared to the volume knob in a fairly conventional fashion with maximum volume at around the 12 o’clock position with most loudspeakers. For the MkII CAAS have devoted more control range to lower volume settings, which in practice means that you have to turn it further round than normal to get a medium output. And if you ignore the company’s steer toward balanced connections the indicator ends up around the 3 o’clock position, leaving me wondering if it would actually be possible to get full output from the power amplifier. In practice I found that it never ran out of range with this linear logarithmic system even when using single ended in- and outputs, and with balanced connections the midday position (-32dB) provided a good medium listening level through 86dB sensitivity PMC twenty5.26i speakers.

Connections extend to three balanced and two single ended inputs alongside outputs on both socket types, the only other connections offered are for the CAAS bus system which allows both pre and power amps to be turned on in one hit. The remote supplied with the EPre is a good match for the preamp with the same solid build and high quality finish, it offers volume, input and mute controls so doesn’t take much getting used to. An on/off button is the only feature that might be a useful addition, having the last used input come up when powering up the preamp would also be nice.


Despite the company name the Elysian 100 Mono-blocks are not full Class A amplifiers yet they have many of the design characteristics associated with that high temperature mode of operation. For a start they have absolutely no feedback, neither local nor global and deliver the first 20 Watts of their 100W output in Class A. Naturally the balanced theme continues here with what the company call coupled symmetric drive, this is a “fully balanced symmetrical differential stage with a small voltage gain” that operates in Class A and drives a Class AB output stage. In- and outputs here are pretty conventional here, just remember to switch in the input selector to the desired one.

At the time that these amplifiers arrived I was assessing a pair of KEF Reference 5 Meta loudspeakers, which are substantial and difficult to move so I dropped the CAAS components into the system to see how they would fare with such a big sonic magnifying glass. The answer is: very well indeed. Initially I used the Elysian 100 power amps with my regular Townshend Allegri Reference preamplifier and this pairing delivered a distinctly Class A sound with a deluxe feel and beautiful tone. They also image very nicely, delivering precise definition of instruments and voices in space with not the slightest hint of grain or edginess, it really is a finessed sound and one that it’s very easy to lean back and enjoy.


It’s also highly transparent to fine detail thanks to very low distortion, I heard things with these amps that my usual and also apparently revealing amplifier failed to unearth. The lack of distortion or noise means that tone is particularly pure, higher notes really shine but avoid anything like glare. These amps are musically intelligent too, reinforcing my feeling that PCM delivers a more engaging sound than DSD thanks largely to the superior timing it seems capable of. Detail is a speciality of the KEFs too so it wasn’t surprising that this pairing proved so effective at unearthing the quiet bits that other amp/speaker pairings miss. They reveal so much about each recording that it’s almost uncanny, with depth of image an obvious strength alongside the degree of finessing that went into the production. I love the way that these amps can deliver detail with so much ease.

Via PMC twenty5.26i speakers the sound is still effortless but it became more apparent that the Elysian monos need an active preamplifier in this situation, there is a slight lack of energy from the passive Allegri Reference that suggests the partnership is not ideal, but that’s hardly surprising. I did enjoy the timing however.

Bringing in the Elysian II preamp delivered more weight and enhanced projection of the sound, this delivered the drive that this speaker needs and the result was both energetic and controlled. Playing some of the new Mingus Three album on vinyl proved a delight with these amps, Class A has always worked well with acoustic music and the piano, bass and drums on this re-release sounded surprisingly good, especially on the disc of outtakes that have a lot more stereo solidity than the original release. The CAAS also worked well with gentler electronica, they don’t have the muscle and grip of a Class AB design but are more than capable of delivering the muscularity of any given bass line whilst defining its textural and tonal nuances.


I used a Linn Klimax DSM straight into the Mono-blocks for a while and got splendid results when using a balanced connection so it was interesting to hear what happened when setting the Klimax’s output to fixed and sending it through the EPre. This is essentially a comparison between volume control systems and saw the preamplifier adding a fine matte polish to the sound that may or may not be on the recording, which was a very polished affair. It also put more meat on the bass line and improved the melodic flow. So, pretty transparent with added benefits which continued to prove very appealing with a range of material, delivering the restraint in Ryan Adams voice and the way that Tom Waits can evoke so much with his poetic words and off kilter rhythms.

Once Carl had made it clear that balanced was very much the operational mode of choice for his amplifiers I tried this mode myself and began to appreciate why. The sound becomes more sophisticated and revealing, with greater dynamic power and significant gains in transparency not least in the bass. There’s a vibrance to the sound that is very appealing and keeps you listening for longer, even timing improved when I moved from single ended to balanced (pre to power) which was a real surprise as previous comparisons on other kit have usually proved the opposite. The Elysian Pre-amp II is clearly an extremely revealing piece of kit that’s capable of serving up mountains of detail in an expansive, room filling fashion.

The Elysian Pre and Monos deliver a well-timed, effortless sound that has the power to draw the listener in to pretty well any type of music. The Class A factor is clear in an absence of grain or sharpness in the context of wide bandwidth, they haven’t simply rolled the highs off, quite the contrary. What CAAS have done is resolve the detail in the music without adding any of the noise that infiltrates so many Class AB designs. I enjoyed a wide range of music with these amplifiers and particularly liked the way that they deliver decent volume levels without any harshness, 20 Watts may not sound like a lot but in practice most rooms/speakers do not actually use more than this. And there’s always 80 more Watts in reserve should you fancy a blast.


Elysian Pre-amplifier II
Type: transistor stereo preamplifier
Analogue inputs: 2x RCA, 3x XLR
Analogue outputs: pre-out RCA & XLR
Distortion THD: < 0.01% @1kHz (0dB level, 2V RMS)
Output impedance: 60 Ohms RCA, per phase XLR
Output voltage: 4V RMS max per phase
Dimensions (HxWxD): 80 x 350 x 330mm
Weight: 8.6kg
Warranty: 5 years

Elysian 100 Mono-block
Type: monoblcok transistor power amplifier.
Analogue inputs: RCA, XLR
Analogue outputs: binding posts
Power output: 100W/8 Ohms, 200W/4 Ohms
Frequency response: 0.8Hz to >300kHz (-3dB) DC coupled
Sensitivity: 1.6V RMS
Gain: 25.5dB
Distortion THD:
<1% @1kHz (100W into 8ohms)
<0.01% @1kHz (1W, 0dBW into 8ohms)
Signal to Noise Ratio: >90dB
Dimensions (HxWxD): 140 x 260 x 340mm
Shipping weight: 11kg each
Warranty: 5 years

Price when tested:
Elysian Pre II £8,000 when tested
Elysian 100 £12,000/pair when tested
Manufacturer Details:

CAAS Audio


preamplifier monoblock power amplifiers


Jason Kennedy

Distributor Details:

Auden Distribution
T +44(0)7917 685 759

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