Geco Audio Vanguard High-Spec – Evolution of Innovation

South Africans are a resilient, resourceful bunch. The hardships of the last 80 years have taught us to ‘make a plan’, and more often than not these plans work. Take access to high-end HiFi, as an example: the torrid Rand exchange rate and geographic isolation has allowed us to generate a small but accomplished cottage HiFi industry.

Geco Audio, created and led by Rudi Marloth, is a good example of local ingenuity. From humble beginnings producing DIY designs and limited run production units, Rudi is now positioning Geco Audio as a bona fide commercial manufacturer. The Vanguard is the brand’s halo product, with local production in full swing and multiple units in circulation.

Manufacturer description

Rather than badly paraphrase the manufacturer’s blurb, we asked Rudi to tell us the story behind the Vanguard, which is indeed interesting.

“The Vanguard concept was initiated from a curiosity to improve a current design of mine but with using simulation software. The concepts came from Douglas Self’s book “Audio power amplifier design handbook” it started just testing improved stages in my initial design but got to a point where I needed to start from scratch to optimise the design properly. The topography of the design is nothing special, all run of the mill stuff. But as they say, the devil is in the detail.

Very early on, I discovered a relationship between how the amp clips and the load it can drive with very low distortion. The closer you get to an equal clip on both positive and negative rail, the better it can handle difficult loads and still keep very low distortions. For example, normal THD at eight ohm is 0,0065%, and it will keep that till near clipping. If you give it a really difficult loads such as two ohms. You will get the THD down to 0,05% at close to full power even below two ohms it will never dip below 0,2% at near full power.

The process to finetune the simulation took on and off the better part of 2 years, including experimentation. I continually tested the concepts on an existing design. Finally, Heinrich Muller and I committed the design to PCB and built the very first prototype. The very first time we switched it on, we knew this was something special. We went through two PCB iterations before finalising the design that we could commit as a commercial product. One of our decisions is to commit to an 80% surface mount layout as we could specify highly tight tolerances, but it made casual building extremely difficult.

The basic design of the amp is as follows. Four power supplies per stereo channel. Fully regulated pre tracking regulation for the input and voltage amplification stage. Separate transformer and capacitor banks for the output stage. Here we aren’t relying on huge capacitor banks but using the big transformers to regulate the voltage. The real magic lies in the input and voltage amplification stages. These are incredibly finely tuned to always give a balanced output to the driver and output stages. The circuit also benefits from no caps in the feedback path and a parallel circuit keeping everything in check. This also ensures a very low output impedance across the entire frequency range”

Versions and competitors

There are two versions of the Vanguard: the standard unit which retails for R52 000 (about $3 400); and the High-Spec, which has larger transformers, slightly higher voltage rails, and thermal protection built in, precision resistors and matched transistors – retailing at R72 000 (US$4 800 based on the conversion rate at the time of writing).

Locally, this places the Vanguard at a similar price level to the Cambridge Audio Edge W, a well-regarded 100 wpc power amp that retails at approximately R50 000, the 350 wpc Rotel RB 1590 (R80 000), or the Audiolab 8300XP. The 300 wpc Vanguard therefore seems to be an attractive proposition on paper.

Initial impressions

AVInside was lucky enough to obtain the ultra-rare High Spec version of the Vanguard from a Geco Audio customer for review. While we are grateful, carting this amplifier around was hard work – it feels like it weighs well north of 40kg, in a relatively compact package. She’s a hefty thing.

The functional Bauhaus-like lines of the Vanguard were universally praised by those that saw it. The partly exposed heatsinks break up the amps lines nicely, and obviously provide for extra airflow over the heatsinks to remove the heat produced.

The amp stands around 3cm off the deck on slightly raised, machined aluminium feet, and the front panel is beautifully clean with a single accent line machined into thick anodised aluminium, with two discrete power indicators (one per channel), and an elegantly engraved logo. The power switch is cleanly (and handily thanks to the chunky feet) placed on the front centre of the bottom panel.

The rear panel finish is not quite up to the high standard of the rest of the Vanguard. There are relatively standard connectors – an IEC connector for power, two pairs of speaker terminals, and two RCA inputs – balanced is available on request according to the manufacturer. There is a small rear nameplate, but the review unit lacked labels for the connectors, and the speaker terminals feel flimsy and insubstantial in operation, especially when compared to competitor offerings. Small details that are easy to rectify, but important.


The importance of this review meant that we brought in a variety of experienced listeners to get a sense of the Vanguard, each comparing it to other AVInside-owned reference amplifiers. The AVInside reference system included an Aurender N100h, MSB Analog DAC with quadrate USB connector, Custom Firstwatt B1 tube preamp, and a choice of Tannoy Royal Westminster SE or custom Altec A7 VOTT speakers. Reference amps include Firstwatt F5, F6 and Cary Audio Design CAD 300SE.

Upon initial power up, the Vanguard has a slightly hard edge to its tonal presentation. This subsides evenly over the next 30 minutes, and as the amp warms up (relatively speaking since it runs very cool), this largely disappears, leaving a sweet, if ever-so-slightly forward presentation.

Doyle Bramhall II and Eric Clapton’s rhythmic rock-blues-boogie on ‘Everything you need’, brings out the best of the Vanguard. Slowhand’s lead guitar sounds textured and can be clearly followed throughout the track. The Vanguard nicely parses the instruments, presenting each separately, with excellent definition. Male voices have weight, and with ludicrous (for our sensitive speakers at least) power, the Vanguard never loses composure.

Depending on what the amp is compared to – and more importantly its source – the Geco Audio amp can sound ever so slightly lean. This is not a romantic sounding amp (unless it is fed a nice bloomy signal from an old-school preamp), and the somewhat hard edge presents itself occasionally, especially on poor quality recordings.

Mavis Staples’ ‘We get by’ is not one of these poor recordings and shows the Vanguards ability to place listeners in front row centre. The sound stage is slightly forward of the speakers (as opposed to the middle seat of the Cary 300b or Firstwatt Class A amps) and left-right expanse is largely determined by the source feeding the Vanguard.

When fed via the Korg Nutube equipped preamp in our system, the Vanguard has a delicious, intimate tonal warmth, however feeding it directly from the MSB DAC (equipped with volume control), the Vanguard presents a much larger stage, but the tonal balance is more clinical.


Astute readers would have linked the above-described characteristics with Rudi’s mention of Douglas Self, who advocated for a blandly-named ‘Blameless’ amplifier. The Vanguard is about as close to a straight wire with gain as any amp I’ve heard. It adds very little of its own flavour yet is never just polite – thanks to its mounds of power and lack of distortion.

The Vanguard’s build quality is decent, and we are certain Geco Audio will improve rear-panel finish and quality in time. The amp runs cool and was trouble free in operation – as it should be considering the premium price tag.

Those that are looking for a ‘sweet sounding’ amp to add flavour to their systems should look elsewhere. However, HiFi enthusiasts who seek an accurate, powerful amp to drive pretty much any speaker you can think of should audition the Vanguard – it represents an excellent prospect in this space.


The Good
Uncoloured, honest and immensely powerful, decent build, and locally made, the Geco Audio Vanguard is a compelling prospect to those seeking an honest gain stage.

The Bad
Rear panel finish needs improvement. Pricing puts the Vanguard up against some competent competitors.

The Ugly
The weight of the High-Spec Vanguard means you should stock up on anti-inflammatories on installation day.

Price as reviewed: Approximately R72 000 in South Africa (approx US$ 4 800)

For more information email, or call Heinrich Muller – +27 82 411 6196

The Geco Audio Vanguard was kindly loaned by a community member and was reviewed as part of the AVInside reference system.

Manufacturer specifications

Power output (claimed): 300 Watts @ 8 Ohms, 600 Watts @ 4 Ohms
THD: 0.0065% @ 8 Ohms
Inputs: Single ended RCA (Balanced available on request)
Input Impedance: 27k Ohms
Dimensions (measured): 440mm (w) x 180mm (h) x 390mm (d)

5 Replies to “Geco Audio Vanguard High-Spec – Evolution of Innovation”

  1. This is a world class review. I read a lot of HiFi reviews and this is up among the best. Well done Sean.

  2. What’s the chance for geco to put up a web site. I’ve searched without luck and surely a product this good deserves a site. If I missed it I appologise in advance, but kindly share a link that includes detailed product information if it exists.

    This review is wonderful and peaked my interest for sure!

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