Old Kiwi brute – Plinius SA-250 MK IV power amp

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Plinius SA-250 MK IV power amp. It’s a monster, and it runs so… hot that my air conditioner has to be set just a few Celsius lower to cool the room down.


By WL Low


I think my dearest buddy, fellow reader and supporter of this blog, Ken will feel most vindicated with this posting of mine (though we tend to disagree on nearly all things when it comes to hi-fi). I am the sort of  hi-fi guy comparable to Vin Diesel’s character in The Fast And The Furious movie franchise, who only goes for American muscle cars.


I only go for class A muscle amps, no class AB or class D bull shit for me. Not that they are no good (in fact some high-end class A/B and class D designs offer state-of-the-art leading audio performance). Yes, there are draw backs aplenty when it comes to class A amps, like they tend to be monster-sized with chunky finger-cutting heat sinks, they are bloody inefficient, they draw current like hell and yet waste most of it as heat dissipated via those chunky heat sinks. There is however only one theory in discipline that makes class A amps worthy of any audiophile’s consideratoin – they tend to pack lots of juice (a.k.a. amperes) to speakers and there”s no handover distortion between class A and B push pull transistor pair, making each musical note seamless in theory. The most common class A amp”s sonic character, if I may use an M&M chocolate copy line, “Melts in your mouth, not on your hands!” That’s how I feel each time I hear a class A amp sing (maybe it’s the heat, stupid! – my sanity cells in the brain tell me).


The object that is the subject of this posting is none other than the Plinius SA-250 MK IV power amp. It’s a brute of a power amp, with the monster size and chunky finger-cutting heat sinks. If weight is any indication of a well-built quality product, how about all 60kgs of it? Thank fully, the manufacturer didn”t forget to put a handle on each corner to assist the transit operations, but the front handles proved more cosmetic than useful, because it is too thick and slippery to hold on to properly, especially with sweaty hands! It was a bitch’s work for two full grown men to carry ring it up to my first-floor man cave! At the back panel, you will find WBT style speaker terminals for 2 pairs of speakers, an IEC power inlet and fused ON/OFF switch and a toggle switch to select between RCA (single ended) or XLR (balanced) inputs. On the front, you’ll find similar simplicity of operations. There’s another ON/OFF switch, flanked by a pair of toggle switches on either sides. On the left hand side toggle chooses between standby/mute and the right hand side toggle switches between class A/B or class A operation. The Plinius pumps out 250W @ 8 ohms load in either class operation, and double the output wattage at 4 ohms load.


The Plinius does benefit from a good power conditioner, it does sound better when drawing its juice via the Torus Power RM8A AVR, compared to direct from wall. The amp draws 1 amp in class A/B mode, and 5 amps in class A mode. It’s a good thing my Torus is still up to the task.


The sound of the Plinius is one that walks the fine line between that of a brute and of a gentleman. While it grabs and controls the drivers of my PMC Fact 8 speakers like a Rottweiler sinking its teeth into one’s neck, the Plinius doesn’t really just sound like a crazy bitch (there, I said it again!) in heat all the way. On the contrary, it’s very civilised on the highs, never untidy and definitely will bite when the music calls for it. The mids are strictly neutral and it presents an open window to the music. Like I said earlier, the bass is brute force strong, I heard more “kick” from kick drums, more defined double bass plucks and more solid, and wholly filled up bass guitar lines. The bass response of my Fact 8 speakers probably dove just a few Hz lower too.


Sound staging took on  deeper and more clearly separated layers of depth, plus the stage opened up wider, and taller too, beyond both sides of the speakers, and outside the room’s physical boundaries. It’s like listening to music on a 2:35 aspect ratio screen and projector AV set up! Talking about AV set up, I finally got to experience transient and dynamic response of an amp truly grabbing a pair of speakers by its balls (or is it mine?……ouch!), musically speaking of course. The Plinius is about the quietest of muscle amps, with no hiss or hum whatsoever heard. There was just silence when doing the ear to tweeter test. I must highlight that so far, I am only describing the sound performance in class A/B mode only.


When switched to class A operation, this amp goes into hyper drive mode – there’s more flow to the sound, to start with. One can hear strings more “tensioned” on guitar, violins more “resonated”, drum skins tightened and vocals honeyed. The mid range gets more “dark chocolatey” with the sweetness of “Old Jamaican” rum and raisin. Bass response also goes harder and punchier, with highs getting just a little more “moist” too. It”s as if every aspect of music making is taken to an extreme joy ride that is much more stimulating for one’s emotions and dynamic senses. I think a comment made by an audiophile sifu most aptly applied, “It’s like all the musicians had finally got their pay cheque and year end bonus all at once!” Makes ya wonder………hmm………….???


Granted, there must be some downsides to this old brute, right? You may ask.


This is where my 1990’s vintage Pass Aleph 0 mono blocks make a fine case for themselves. Even in class A operation, the Plinius just fails to present the ninth degree of transparency, like the last bit of piano wood harmonics and string texture, the last bit of piano foot work, like on track 6, And So It Goes, from The Well album by Jennifer Warnes, so evidently heard via the Pass Labs. On recordings with delicate high hat and cymbal play, the halo of air surrounding the shimmer is also more moist when heard via the Pass Lab Alephs. Even breathy and saxophone finger play, and brass tube resonant harmonics are more pronounced via the Pass pair of mono blocks. If the finer details in life are more important compared to the broad brush, big bold strokes of musical picture presented by the Plinius, then the Pass Alephs still hold their magical single-ended class A spell.


The girly Lily Chen sounds more sophisticated, lustfully seductive even, especially when played via the Plinius SA-250 MK IV in class A mode. The lush orchestral backing with leading violin and viola sections certainly sounds realistically resonated on some the tracks here.


Thinking about getting an SA-250 MK IV for yourself? Here’s my two cents of market research. The popular Plinius SA series are rather long running in production. Like its more famous smaller brother, the Plinius SA-100 was available in 4 revisions. Most preferred is the MK II followed by MK I and MK IV in equal measure. The MK III is for some reason the most un-loved of all due to its too neutral tonal balance as some would say. I’ve only known the SA-250 to be available locally in MK IV guise as the most desirable version. It was produced starting sometime in 1999 and ended its production run by 2004. Plinius superseded the SA-250 model with an SA-Ref model in 2005. Even though all SA-250 shared the MK IV moniker, those produced after 2003, had revised protection circuit, making them less prone to fault and less sensitive to false alarms, as witnessed in those pre-2003 production units. One must probably also run the Plinius in air-conditioned rooms (in our tropical environment) as they will run hot, and I mean skin- burning hot, at the edges of those chunky heat sinks. Many pre-owned examples may have been used to drive too low speaker impedance (way below 4 ohms), and may have been repaired with improper bias setting, resulting in the overly sensitive tripping of the protection circuit on the older production units. While the Plinius SA-260 MK IV are a brute force, they are still not the Krell KAS series level type of brute yet.


At their current 2nd hand market prices, which could be anything between RM$9-13.5k, based on condition and year of manufacture, the Plinius is currently trading at just barely 1/3 off their original retail prices when new. This makes them a worthy choice of high-end, high-power amplification for those who are power mad, or who just happens to own power-hungry speakers. Just be mindful of the conditions that you intend to accommodate them in your home, as mentioned above and if you think there’s potential, then the Plinius is a mighty fine used acquisition.


It’s now my high power reference!

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