Sometimes, only an integrated amplifier will do, even if you've 15k burning a hole in your pocket. AVID's gargantuan Sigsum is here to challenge any bias toward separates Maybe one grows less ornery with age, or perhaps there was a nice guy inside of me waiting to crawl out from my crotchety self. It's just that, only a few years ago, the frustrating elements of AVID's Sigsum integrated amplifier would have had me cursing Editor PM for asking me to review it. So, there's minimalism here, and there's contrariness, and that's just the lack of remote control. In a product a fiver short of 15,000. Let's look at this in context, even though this isn't the place to argue about integrated versus separates. You are seasoned audio enthusiasts and you know each have their strengths and weaknesses. With an integrated amp, there's no possible mismatch between the preamp and power amp, you save the cost of an interconnect, etc, while separates deliver better isolation between pre and power sections, provide an easier upgrade path, and so on. No Wallflower You can see the dilemma this presents at 15k. Simply put, there are far too many pre/power combinations available for this money. To which you might counter: 'I only have space for one component' or 'It saves me an AC outlet'. What the Sigsum does, however, is deliver a unit so massive, so heavy, so over-engineered that it looks like it eats twee SET tube amps for breakfast. Either way, the Sigsum is neither shy nor retiring, occupying a capacious 471x190x500mm (whd) and weighing 31kg. The first doesn't matter, because it's no worse than any high-end stereo power amp from the likes of Mark Levinson or Krell. But 31kg? I note the engraved 20mm-thick alloy front panel, the 3mm steel chassis, the huge toroidal transformer all very reassuring, but arguably a little more voluminous than it needs to be. The Sigsum offers four line inputs (two balanced on XLRs and two single-ended on RCAs), an MM/MC phono input with gain/loading adjustments under the chassis, a preamp output, and single sets of 4mm speaker cable binding posts Back to context. I realize most of you do not change cartridges on a daily, weekly, monthly, or even annual basis. For you, the location of the phono stage DIP switches is irrelevant. But to place them under a 31kg amp? It's one thing to site them beneath MoFi's UltraPhono [HFN Mar '20]: it's the size and weight of a deck of cards. But as the user who spends 15k on an amp is also likely to have more than one cartridge, this inconvenience is unfortunate because the phono stage is truly excellent. Its options cover pretty much all mainstream MM and MC cartridges you might encounter, offering gain settings of +40dB, +60dB and +70dB, the impedance of 100, 300, 500ohm, 1kohm, 5k, 10k and 47kohm, and capacitance levels of 100, 200 and 500pF. But I let out a sigh recalling AVID's Pulsus, on which the Sigsum's phono stage is based and which I reviewed back in 2012 it consists of two small boxes, and it was so easy to flip over the 1kg preamp section. Weapon Of Mas Instruction I realise we're venturing into the let's-agree-to-disagree arena, but AVID's CEO Conrad Mas has firm beliefs here. This amp is equipped with one of the best volume controls on the market, a lovely ALPS RK50 device, each costing AVID a small fortune, so why no remote? Mas stated flatly that, for him, 'The Sigsum is all about sound and build quality. He further explained that none of AVID's amps offer remotes, having come to this conclusion after discussions with ALPS. Still, that doesn't explain why US tube brand VAC, which uses the same pot in its flagship Master Preamplifier [HFN Mar '21], has a remote and I don't recall that suffering for it. Mas also argues that turntables aren't remote-controlled and 'LP users are used to getting up and down, so adjusting the volume isn't an issue. Maybe not for him. So, once more, context. You are unlikely to site a 31kg beast of an amp next to your elbow. That said, this has a headphone output, so you'll need a long cable for your cans or perhaps you will then place the Sigsum next to your hot seat. In which case, the remote control issue is moot. Whining over. Sigsum its name comes from 'the SUM of two SIGnals' is impressively styled, easy to use (phono settings and remote control aside, that is), and provides, in addition to the phono input, two RCA line inputs and two balanced XLR inputs. Derived from AVID's Reference Pre and Mono amplifiers, the Sigsum's preamp section and phono stage reside on one PCB, while the power amp is configured as two mono modules. Power is provided by a massive circa-1kVA mains transformer, with a separate PSU supplying the phono stage. Take A Seat... Unpacked and located, the Sigsum is as straightforward a product to install as you could imagine, provided you set the phono stage DIPs before siting it. The back is fitted with top quality connectors for both the XLR-balanced and RCA single-ended inputs, the speaker terminals are multi-way, and the seasoned user probably won't even need to look at the owner's manual but once to find the on/off switch underneath the unit, at the front.As you can imagine, I was not minded to try three or four cartridges given the effort required to change the settings, but the phono stage deserves a top-flight moving coil, and I wouldn't be surprised if this was voiced to optimize the performance of AVID's Boron or Reference Ruby [HFN Apr '21 and Nov '20]. I own neither, so I settled on another make of MC with a gem cantilever and an evergreen Ortofon 2M Red [HFN Oct '08] for MM duties. Balanced inputs were tested with the Otari MX5050 open-reel deck. One thing's for certain: this amplifier doesn't fear hungry or cranky speakers (or cranky reviewers). Most listening was undertaken with Wilson's Sasha DAW floor standers [HFN Mar '19], which proved beneficial because I have been impressed by the lower registers of Bryan Ferry's remastered LPs. What the Sigsum exhibited was superb slam, accompanied by an analytical prowess in the bass, all expressly revealing of the differences between the original release of Boys And Girls [E'G EGLP62] and the remastered edition [Virgin/UMC BFLP6]. This is serious stuff, especially when purists insist that first pressings can never be bettered. Classic Cuts OK, so we're talking about remastering from 36-year-old tapes (nothing to worry about, in practice, when you think of reissues of Sinatra's 1950s LPs or even 1960s tapes), but such forensic skills speak of clarity, transparency and freedom from mush which I suppose is what solid-state devotees consider to be their preferred topology's specialty. What was so refreshing about AVID's Sigsum was the sheer openness of its sound, despite a slight lack of warmth noted on Ferry's vocals for the aching 'Slave To Love'. Noratel transformer [lower right] is at the heart of the big PSU feeding the two stacked power amp modules [on heatsinks, lower left]. A separate supply [top right] services AVID's MM/MC phono stage [top left Despite my possibly misguided new persona of Mr Nice Guy, I decided a torture test was in order, so I fed the Sigsum with what could be either a visit to heaven or a trip to hell. I am not a huge fan of massed violins, but my forays into reel-to-reel have forced familiarity with such quaint outfits as 101 Strings. They recorded a delightful (as might be used by Barbara Cartland) homage, 101 Strings Play The Best Loved Songs Of Rudolf Friml And Sigmund Romberg [Audio Spectrum ASE5003 open-reel tape], with ditties from operettas including 'The Desert Song' and others of that ilk. New Romantic Ordinarily, a subtitle reading 'Favorite Romantic Melodies Of Yesteryear' would be my signal to up and leave the room, but via the Sigsum, what greeted me was silky, sweet, and even cosseting. The soundstage was suitably wide, just deep enough and possessed of enough air to give the proceedings a welcome lift. I was reminded of sessions in the late Alastair Robertson-Aikman's legendary SME Music Room, transporting me to a theatre and suddenly imparting in me a craving for sherry which I haven't touched in 50 years. To ensure that this wasn't a fluke, as the Sigsum was exhibiting almost valve-like behavior in the upper registers, I moved onto more strings, this time from Andre Kostelanetz, whose The Academy Award-Winning Shadow Of Your Smile And Other Great Themes [Columbia CQ811] is a feast of orchestral versions of 1960s film music. The title track alone confirmed that, indeed, the Sigsum's upper registers did not exhibit any brittleness, while the transient attack of staccato strings was as lightning-fast and precise as one would expect of a solid-state behemoth. Back with vinyl, and George Harrison's All Things Must Pass 50th Anniversary [Capitol 3567012] vinyl box set supplied ample proof that this was as clean and uncolored in the mid band as it was up top, evidenced in both George's vocals intimately familiar to any Beatles fan and the superb guitar work throughout the set, but especially on 'Wah-Wah'. I am no guitarist, but I suspect the neutrality of this amp will empower those who are to identify which parts are played by Clapton, which guitars were being used and other elements which eluded the liner notes. Beach Bound My new-found test for textures is the gorgeous remastering of The Beach Boys' Feel Flows [Capitol 02508 80212], mainly the Surf's Up tracks, not least because of the special effects that Brian Wilson was playing during this period, post-Pet Sounds. No puns intended, but there's liquidity to the entire LP, especially 'Don't Go Near The Water', 'Feel Flows', and the lush 'Disney Girls'. In a word, like the music itself, the Sigsum sounds classy. Hi-Fi News Verdict AVID's Sigsum targets users who need or prefer integrated amplifiers, have an outboard DAC, rarely change cartridges, favor minimalism, and demand indestructibility. If those apply, then the Sigsum ticks all the boxes, with clear, analytical sound, an air of reliability and longevity, and the kind of straight-out-of-Metropolis looks (Lang, not Siegel and Shuster) that scream 'bombproof'. Ah, but for a remote! Continuous power (1% THD, 8/4ohm) 128W / 225W Dynamic power (1% THD, 8/4/2/1ohm) 142W / 265W / 459W / 535W Output imp. (20Hz20kHz/100kHz) 0.0240.090ohm / 0.66ohm Freq. resp. (20Hz20kHz/100kHz) 0.02dB to 0.14dB / 0.67dB Input sensitivity (for 0dBW/110W) 33mV / 355mV A-wtd S/N ratio (re. 0dBW/110W) 89.3dB / 109.7dB Distortion (20Hz-20kHz, 1W/10W) 0.00040.017%/0.00090.028% Power consumption (idle/rated o/p) 56W / 372W (1W standby) Dimensions (WHD) / Weight 471x190x500mm / 31kg Price 14,995
