An amplifier has to be something truly magical to follow, let alone partner the Audio Research SP16 pre-amp. When I reviewed it for the May issue, that delicious control unit, 'affordable' by ARC standards, reminded me of why I fell in love with the Minneapolis brand above almost all other post-transistor valve amp makers. The associated stereo power amp, the VS55, merely reaffirms my faith. The warmth and appeal of the combination's sound I such that, if at any time in your 'audio past', you auditioned, borrowed or (lucky you) owned a piece of Audio Research equipment of 1972-1990 vintage, you're gonna wonder who requisitioned the time machine.
Don't choke on your cornflakes: I don't mean that the VS55 sounds 'old'. I'm suggesting, simply, that it's as commanding and instantly-recognisable-as-a-champion-product as were ARC classics of yore, like SP-10s and D-150s. But that's it - the rest is pure 2002. If synecdoche is your preferred literary conceit, then the most indicative departure from past practice is the VS55's completely new look; otherwise, you can take it as a given that the company's return to past values is NOT an exercise in retro.
I cannot even name an earlier Audio Research power amp which lacked a front panel - any reader with an elephantine memory please help out here - even if they were open-chassis types without 'sides': you'd still get a free-standing front panel. Thus, the VS55's styling might throw you. Instead of the usual full-width, brush metalwork-with-black handles 'lab-look' which has always identified the company's power amps, the VS55 displays its tubes with pride. While EC law dictates the presence of a tube cage or some form of protection on the grounds that valves run too hot for us to be exposed to them (Brussels typically contradicts itself, as low-voltage halogen lighting runs hotter and no protective screen is required), there will be a cage of some sort available; the review sample arrived au naturel.
Because of the absence of a fascia, the VS55 seems small. Moreover, its footprint is only 14x14in and the height a mere 7in, so the unit is truly compact. This gives it a bijoux visual appeal, as does an overhead view in which the unit is split into silver and black areas, the silver being a milled, anodised plate. The black area continues down to the four sides of the chassis.
What remains of a frontal area contains an on/off rocker switch and a green LED power-on indicator. The back surface contains connections for 4 or 8 ohm speakers via multi-way connectors (hurrah - no screw terminal strips!), phono sockets for single-ended line input, contact points for testing the bias, an IEC mains input and a holder for a user changeable mains fuse. The unit can also be switched on automatically with the preamp through a 12V trigger. Underneath are four elastomer feet, which provide nice mechanical damping.
Viewed from above, the front of the VS55 contains three 6N1P driver and input tubes, each wearing a damping ring. Behind them are four robust, rich-sounding, Russian-made 6550EHs and some serious power capacitors. Finally, at the very back of the horizontal surface is the only part hit savagely and unremittingly with the ugly stick: poorly-painted mains and output transformers just screaming to be covered with a can of some sort, as in the manner of Quad valve amps (old and new) or Nightingale's ADM30. Naked, they look like something borrowed from a well-used Dynakit. If the forthcoming EC-approved cage is full-sized rather than dimensioned just to protect the tubes, the look of the transformers won't jar so much. Audio Research, shame on you...
As far any company mission statement might go, it's clear that the VS55 is targeted at users such as I, those who have always felt that the sweetest-sounding amplifiers seem to be classic push-pull designs with 35-75W/ch ratings. Why, I don't know, but a lot of the 'true greats' seem to fall into that category, and ARC itself has always had a dandy 50- or 60-watter in its catalogue. In the case of the VS55, the rated output is 50W/ch continuous from 20-20kHz, with clipping at 52W. The power bandwidth has -3dB points at 12Hz and 50kHz, and frequency response is 1Hz to 60kHz. Overall negative feedback is 12.5dB, and hum and noise are stated as less than 0.2mV RMS, -100dB below rated output.
As with the listening sessions for the SP16, the VS55 was part of my regular system consisting of Wilson WATT Puppy System 6 and LS3/5As, Marantz CD12/DA12 and, for analogue, the Linn LP12/Ekos/Arkiv front-end). Reference power amps included the Quad II-fortys, Radford STA-25 and Dynaco ST70, the alternate preamps for comparison were the Quad QC24 and Musical Fidelity Nu-Vista, while wiring was Transparent Ultra and Kimber Select. Also, as mentioned in the SP16 review, Sonus Faber's Cremona matched the VS55 with the kind of synergy you only expect from single-make packages.
Read more about the VS55 on Page 2.