Integrated Amplifiers

Two years ago, when Musical Fidelity relaunched its Nu-Vista hardware line with the four-box PRE/PAS amplifier system [HFN Mar ’23], owner Heinz Lichtenegger – whose Audio Tuning company had acquired the brand in 2018 – confirmed plans for two sibling integrated amplifiers. The first of those, the 800.2, surfaced a few months later [HFN Aug ’23]. Now, perhaps belatedly, comes the turn of what Lichtenegger told us would be the ‘lower-power’ Nu-Vista 600.2.

And yes, this amplifier’s claimed 2x160W/8ohm output puts it some way behind the 330W/8ohm rating of both the 800.2 and Nu-Vista PAS [see PM's Lab Report]. But only the most power-hungry audiophile would consider the 600.2 a lightweight, its beefy stature emphasised by its size and mass. Tipping the scales at 36kg, it’s just 5kg less hefty than its bigger integrated brother, and measures the same 483x187x510mm (whd). In other words, this isn’t quite a ‘mini me’ version.

Tube tactics

Viewed front on, the 600.2, with chunky aluminium chassis offered in black or silver, appears identical to the 800.2. It also shares the same key technologies, chief among these being the nuvistor valves in its Class A line/preamp stage. Introduced by RCA in 1959 and claiming performance and reliability improvements over glass vacuum tubes, these compact metal-bodied devices are now ‘almost extinct’, says MF. Fortunately, it has a plan [see boxout].

Above: Built as two mono amps, with two transformers and PSUs [left], into a single chassis, the 600.2 has one pair of 6S51N nuvistors [right] and two complementary pairs of Sanken output transistors per channel [top and bottom]

Just as the 800.2 was an upgrade on the Nu-Vista 800 [HFN Nov ’14], the 600.2 reimagines the previous 600 – only here the changes are more comprehensive and bring it far closer to its costlier stablemates. Refinements are down to the component level, including higher quality polypropylene capacitors and the use of input-switching relays in place of the older model’s IC-routing. More importantly, the Class AB power stage – like that of the 800.2 and PAS – now leverages Musical Fidelity’s Titan architecture [HFN May ’10], where each transistor (four per channel, in this instance) has a corresponding ‘high current’ bulk supply capacitor. This, says the company, ‘allows more immediate access to stored energy’ aided by a ‘much lower impedance path’.

Additionally, the 600.2 features a completely revised and streamlined PCB layout, including a shielded tray for the preamp circuitry to improve noise isolation. And while the amplifier utilises pairs of toroidal transformers in its fully balanced, dual-mono design, a switch-mode PSU is now only employed to boot the unit out of standby mode.

Balanced bliss

With space now saved inside, MF has been able to bolster the 600.2’s connectivity. There are two balanced XLR line inputs, rather than the 800.2’s single option, ensuring the 600.2 is instantly compatible with the range’s Nu-Vista DAC [HFN Mar ’24] and Nu-Vista Vinyl 2 [HFN Feb ’24] phono preamp. A variable balanced XLR output has also been added, filling out a back panel that offers RCA line ins and fixed/variable outs, plus twin sets of speaker terminals for bi-wired set-ups.

Around the front, the amp carries the Nu-Vista series’ new, larger display, with light and dark modes, each with a VU meter option. Either side are rotaries, one for source selection, the other for adjusting the 600.2’s laser-trimmed volume control, which progresses from an indicated –95.dB to +7.0dB in claimed 0.5dB steps.

Musical Fidelity’s remote [pictured below] matches the amp by being both big and weighty, and its controls are sensibly spaced and cover off (nearly) all functions – missing is a ‘Lighting Mode’ key to correspond to the one on the 600.2’s front panel. This means you’ll need to go to the amp to choose if you want the panel to enter screensaver mode, or the four 6S51N nuvistor valves, visible through a grille in the top plate, to be illuminated (orange during ‘warm-up’, blue at ‘full thermal equilibrium’, red when the amp is muted).

Speaking of which, I’m not a fan of the way the mute function works, as once activated the amplifier can’t be unmuted by a tap on the volume up or down keys – you must remember to hit the Mute button again. But this is a trifling inconvenience, and otherwise the 600.2 is easy to set up and use. Spikes and flat feet are supplied, and there are even four small adhesive pads to be added to the bottom of the handset, should you not want to mark your listening room coffee table…

Above: The Nu-Vista 600.2 has six line inputs (four on RCAs and two balanced sets on XLRs), plus fixed (RCA) and variable outs (on both RCAs and XLRs). Pairs of very substantial loudspeaker cable/4mm binding posts support bi-wiring

Velvet vibes
For those tempted by Musical Fidelity’s 800.2 but unable to stretch to the price, the 600.2 is more than just a consolation prize. The performance traits of the premium model are mostly replicated here, thanks to a combination of smoothness and weight that gives its big, musical pictures a lush, velvety edge. It’s a nicely detailed sound too, drawing the listener in with a fluent midrange and rugged lower octaves that ensure the amp’s inherent power is never forgotten. That said, it doesn’t appear quite as light on its feet as the 800.2, but neither does it come across as sluggish.

‘All Secrets Known’, from Alice In Chains’ Black Gives Way To Blue [Parlophone 50999 308266 2 5], is a good system challenger, being a dense, multi-tracked piece full of distorted guitars, thundering drums, and the band’s usual vocal harmonies. The 600.2 really digs into the production, building a soundstage full of fat, well-defined textures that fully revealed the low-end potential of my B&W 705 S3 Signature standmounts [HFN Aug ’24]. It sounded powerful yet clean, and with the impression that the amp had more to give, rather than being under strain.

Monkee business

The album’s title track is less dense, with Elton John’s guest appearance on piano accompanied by strummed acoustic guitar and gentle bass. As a eulogy to the band’s former lead singer Layne Staley, it’s a song of heartfelt emotion, and the 600.2’s rendition brought that to the fore. There was naturalness to instrumental and vocal tones, and authenticity to minor dynamic flourishes that made for an involving listen.

Used with a Hegel Viking CD player [HFN Sep ’23] and Matrix Audio Element X2 Pure DAC [HFN Dec ’23], the 600.2’s presentation of fine treble detail wasn’t emphatic, as shown by the cymbals and hi-hats on The Monkees’ ‘Last Train To Clarksville’ [Greatest Hits; Rhino, 192kHz/24-bit]. Yet Davy Jones’ chatty intro and vocals to ‘Daydream Believer’ were crisp and succinct, and by avoiding any explicit HF sharpness, the 600.2 gave the ringing guitar of Robert Plant’s ‘If I Were A Carpenter’ [Fate Of Nations 2009 remaster; Es Peranza] download a flowing, relaxed feel. Musical Fidelity talks of its Nu-Vista amps being ‘calm and smooth’ by design, and that’s very evident here.

Burst mode

Of a completely different ilk is Lady Gaga’s ‘Disease’ Mayhem, [Interscope; 44.1kHz/24-bit], with its electronically sculpted beats and processed effects. This let the amplifier show its more playful side, particularly in the staccato, bouncy verse where it brought such power and punch to every element that the track sounded ready to burst. Where before I’d been focusing on midrange tones and feel, now I was enjoying the amp’s exuberance and controlled, driving bass.

Above: Solid alloy remote offers control over input, volume, mute and display brightness

This side to the 600.2 makes it a good fit for the riffs and rhythm sections of rock music. Carlos Santana’s slickly produced cover of The Stones’ ‘Can’t You Hear Me Knocking’ [The Greatest Guitar Classics…; Arista 88697772332] sounded lively and impactful, those VU meters jumping along to the widespread drum track and wah-wah guitar licks. Similarly ear-opening was ‘Black Sabbath’, from the eponymous album [BMG/Sanctuary 2730324]. The 600.2 confidently placed the tom-tom drums behind Ozzy Osbourne’s vocal, giving each its own distinct texture and position. The steely tone of Tony Iommi’s guitar, as he lay down that famous ‘Devil’s tritone’ riff, was spine-tingling.

What comes to mind when listening to MF’s newest integrated amp is the old ‘iron fist in a velvet glove’ trope. It’s not as powerful as the 800.2, but for those with less than cavernous rooms or moderately obliging loudspeakers, what it provides in wattage is surely enough – and it comes allied to a sound offering easy warmth and fluidity. Playing Bruckner’s Ninth Symphony Gewandhaus Orchestra/Andris Nelsons [DG; 192kHz/24-bit] was as much about the delicate touch brought to strings and woodwind as the massed power of the brass. Make no mistake: this all-analogue amp has all-round appeal.

Hi-Fi News Verdict

By undercutting the Nu-Vista 800.2 by some £3000, while leveraging the same technologies and offering more connections, this amplifier will find plenty of admirers. The 600.2 gives ground in terms of power, but is still more than gutsy and maintains the series’ sonic signature. Soundstages, ostensibly shaped by those nuvistor tubes, are big, rich and satisfying, making every listening session a joy.

Sound Quality: 89%