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REVIEW: Aspen Amplifiers AKSA LifeForce Amplifier (SS)

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Model: AKSA LifeForce
Category: Amplifier (SS)
Suggested Retail Price: unknown
Description: 55wpc & 100wpc versions available
Manufacturer URL: Aspen Amplifiers
Manufacturer URL: Aspen Amplifiers

Review by DSK ( A ) on December 12, 2006 at 18:55:04
IP Address: 211.28.154.201
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Owner Review: ‘AKSA LifeForce’ power amplifier

Foreword:

I have previously shared most of this content with fellow AKSA owners in the Aspen Amplifiers forum on Audio Circle. However, I continue to be so impressed by this amplifier that I thought I’d tidy them up into a more formal review for the interest of enthusiasts who haven’t heard the new AKSA Life Force amps and may not have heard of Aspen Amplifiers, the company. The number of times I’ve been moved to do this, during the many years that this obsessive hobby has had its boney fingers gripped tightly around my neck, could be counted on one hand. But, if I can help someone else onto the right path to achieve their audio nirvana I will be happy that I have given something back. I am grateful to the people who have helped me along my own path. Be aware that I am not a professional reviewer (a fact that will no doubt become evident as you read on) and that my ears may or may not be any more golden than yours. So, feel free to take this review with a large pinch of salt.

Intro:

Until about two and a half years ago, I was using the Plinius SA100 mk3 power amp. This was purchased after listening to a variety of amps from Audio Aero, Consonance, Melody, Electrocompaniet, Perreaux, Musical Fidelity, Arcam, Rotel, NAD, Elektra, ME, RedGum etc. The Plinius, rated ‘Class A’ by Stereophile, was a nice amp and I used it for several years. However, two years ago I had the opportunity to audition the AKSA Nirvana Plus amp in my system and compare it to the Plinius. Despite reviews praising the Plinius’ bass, the AKSA amp had more articulate bass, better transient attack and seemed a little more extended on top. Overall it was a more transparent amp than the Plinius, which sounded a little soft, veiled and ‘blowsy’ or romanticised in comparison. I also auditioned the Bel Canto EVO2 in my system and, although very clean sounding, it lacked emotion and life. So, I upgraded to the AKSA Nirvana Plus and used it happily for two years, until…

In July 2006 I had the opportunity to audition the new AKSA LifeForce 55 in Hugh Dean's system (which I have come to know quite well) for a few hours, then in my own system for a few days. Shortly after, the LifeForce 100 (subject of this review) was released and I eagerly snapped it up. The LifeForce 100 (100wpc) is simply a more powerful version of the LifeForce 55 (55wpc) and I’ve had it in my system for several months now. All marketed AKSA power amps are solid state designs.

First Impression:

Upon installing a new component I usually hear 2 or 3 significant differences within the first few minutes, then listen longer to ensure that these differences are actually improvements, and to identify the less obvious differences. The most obvious areas of improvement upon firing up the LifeForce55 were: bass power and articulation; dynamic headroom/effortlessness; purity across the entire audible range; and openness and imaging. However, even more fundamental than this was an immediate and overwhelming impression of listening to a live performance rather than a hifi system. Everything just sounded ‘right’, natural and alive.

Bass:

It was immediately obvious that the LifeForce amp has plenty of stump-pulling grunt. Bass slam and quality were easily superior to the AKSA Nirvana Plus amps, with greater weight, impact, detail, and control. The palpability and detail of the bass was improved and we heard chords in the bass that were not noticed previously. The LifeForce 55 and 100 amps sound identical, other than the LifeForce 100 possessing even greater power reserves and control. The LifeForce amps really are the proverbial iron fist in a velvet glove. Though there are some higher powered amps that may equal the slam and dynamics of the LifeForce, I haven’t heard any that are also able to make the bass sound as realistic, palpable and acoustic as the LifeForce does. Crisp and punchy, round and growly, or heavy and gonad rattling, depending on the particular recording.

Mids:

Before hearing the LifeForce, there was always a little voice in the back of my head telling me that I would only find true satisfaction (in the mids) with a tube amp. Several months before the release of the LifeForce I auditioned Hugh Dean’s reference Glass Harmony tube monoblock amps (hot class A amps that were unfortunately too inefficient and expensive to be brought to market). Simply lovely, with a more complete harmonic envelope than the AKSA Nirvana Plus, this is what I had been yearning for. Overall though, the LifeForce is a better amp than the Glass Harmony. Compared to the great tube amps, the LifeForce may not quite have that very last iota of tube ‘wetness’ or ‘magic’, but its transparency, ultra low distortion and purity allows a far more complete and realistic harmonic envelope than any solid state amp I have heard and some tube amps too. The mids are wonderfully open, uncoloured, organic and convincingly real.

Treble:

The LifeForce is a wide bandwidth design and this is evident in the lack of rolloff in the higher frequencies. It is more extended and open than the Plinius and much more refined than the AKSA Nirvana Plus. Shortly after release of the LifeForce, Hugh replaced a capacitor that acts as a low pass filter, reducing any RFI and high frequency noise. This change has been retrofitted to all supplied LifeForce amps. After the capacitor change, the top end became even more open, detailed and natural, with the elimination of a very slightly hot top end that had masked some inner detail and soundstaging information. I really didn’t expect to hear a difference, but the change was unmistakable.

Soundstaging & Imaging:

In my experience, tube amps typically portray a more complete and convincing portrayal of the soundstage and images thereon than their solid state brethren. They seem to have greater depth of image and better front to back layering. The LifeForce equals anything I have heard in these respects. I think this is perhaps due to the exceptional transparency and the completeness of the harmonic envelope that it offers. Whatever is on the recording, you will hear it, or in this case ‘see’ it. Whether a small, intimate studio or club performance, or a symphony in a large hall, you will not have to search for the audible cues to create an accurate picture of the venue in your mind’s eye.

Also impressive, is that the sense of the venue acoustic is not diminished during dynamic orchestral passages, there is no congestion or flattening of the imaging or soundstaging. The performance just continues in a completely open and unhindered manner. This control imbues a sense of power and majesty that is only evident from the very best amplifiers and seems to instill in the listener a sense of greater dynamic range, or at least greater effortlessness and control within the dynamic range. Very few amps seem to get right the ‘swell’ of an orchestra, homogenizing the various instruments into one big lump. Not so with the LifeForce.

In addition, the clarity and detail floating up from instruments deep in the soundstage on classical music is extraordinary. On many amps, these instruments are buried or just hinted at.

Character:

The LifeForce is a very neutrally balanced amplifier. Neither warm nor cold, it will simply allow the personality of the rest of the system to pass through unaltered. Simply spice to taste with your choice of pre-amp. In concert with the GK-1 tube hybrid pre-amp, I have found the tonal balance to be superb.

Perhaps most impressive is the sheer transparency, openness and lack of colouration afforded by the LifeForce. Along with the quietness of the amp, these traits allow tremendous inner detail to emerge in a completely natural manner and invoke a strong sense of purity and refinement. Thankfully, there is no solid state ‘thinness’ or ‘leanness’ to the sound of the LifeForce, it has excellent body or ‘meat on the bones’.

Strings and vocals are more lifelike and palpable than other amps I’ve heard to date, with a beautiful balance between the body and breathiness of voices, and also between the body and strings of stringed instruments. Percussion and guitar plucks are superb, with cleaner and faster initial attack, and the ability to float up more effortlessly from a quieter soundstage, thus sounding more pure and 'in the room'.

The LifeForce portrays vocals, drums, percussion, piano and stringed instruments in a more convincingly lifelike manner than any amp I have heard to date, with wonderful timbral and tonal accuracy.

Despite, or perhaps because of, the high levels of transparency and inner detail, the LifeForce is an extremely musical and engaging amplifier. In this regard, the listening experience is more like that from a good tube amp than a solid state one. Differences between various recording techniques and equipment are even more obvious than ever, as are any underperforming components in the system.

When we listen to bands at clubs there is a real weight to the bass lines that underpins and carries the entire performance, giving it a real sense of rhythm and life. Most stereo systems do not reproduce this feeling very well, leaving a comparatively lightweight and unconvincing performance. The LifeForce amps do this better than any I have heard, giving the performance a real (dare I say it) … Life Force.

It’s cliché I know, but the system has disappeared and I’m just enjoying the performances. The music has more poise and delicacy, the emotion and artistry just flowing out effortlessly. The suspension of disbelief is no longer periodically interrupted by artifacts that remind you that you are not at a live event (quality of the recording permitting). There is no conscious sense of listening to a tube or solid state amp, just real performances.

Conclusion:

As may be well evident by now, I am rapt in the LifeForce. I’ve spent many years in this crazy, obsessive hobby and believe that I’ve finally found an amplifier that I can live with for the long term. Matched with the AKSA GK-1 pre-amp, I am experiencing wonderfully realistic and emotional performances that I have not heard bettered, even by the systems I’ve heard with a total cost in the 60k to 80k range. On decent recordings, I am more consistently ‘in the room’ with the performers than ever before.

Though the LifeForce may be just the tiniest smidgeon short of great tube amps in harmonic completeness, it fares better in this regard than any solid state amp I have heard. It is impressive everywhere else (even in a ‘cost no object’ sense) and is a beautifully balanced amplifier that plays music in a very refined and engaging manner. No grain, no glare, no peakiness, no unnatural emphasis of any frequency range. It just sounds REAL.

Is it the proverbial straight wire with gain? Well, overall it is the closest thing I have heard yet.

Perhaps I can finish with the initial teaser I sent Hugh after hearing the LifeForce in my system for the first time...

“Hugh, F@#K THIS AMP is GOOD!”

By the way, this review is written purely from a performance point of view, without regard to price. IMHO you would normally need to spend pretty serious money to achieve this sort of performance. However, compared to the cost of some of the amplifiers with similar overall performance, the LifeForce is a true bargain. The only catch is that you will need to build it yourself or have someone do it for you. Hugh may be able to put you in touch with someone. More info, specs and pricing details are available on his website. (See http://www.aksaonline.com/index.html)

Disclosure: I have no vested in interest in AKSA other than being an immensely satisfied customer.


Product Weakness: Harmonic completeness just slightly short of the best tube amps. Currently only available for DIY.
Product Strengths: Openness, effortlessness, dynamics, inner detail, imaging, transparency, neutrality, PRaT, sounds like REAL music.


Associated Equipment for this Review:
Amplifier: AKSA LifeForce
Preamplifier (or None if Integrated): AKSA GK-1 (tube hybrid pre-amp)
Sources (CDP/Turntable): SqueezeBox2 (Bolder mods & Bolder Deluxe PS)
Speakers: Selah Audio ScanSpeak References (Deluxe crossovers, sealed version)+ Rythmik Audio sealed subwoofer.
Cables/Interconnects: Audience Au24 ICs, Eichmann Nightingale SCs, Eichmann AC Enhancer PCs, PS Audio xStream Plus PC.
Music Used (Genre/Selections): Varied
Room Size (LxWxH): 24' x 19' x 9'
Room Comments/Treatments: DIY bass traps and fibreglass wall panels.
Time Period/Length of Audition: Over 6 months
Other (Power Conditioner etc.): Dedicated 20A lines, PS Audio High Current Ultimate Outlets (source & pre-amp).
Type of Audition/Review: Product Owner




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Topic - REVIEW: Aspen Amplifiers AKSA LifeForce Amplifier (SS) - DSK 18:55:04 12/12/06 ( 1)