Pre/Power Amplifiers

It was at Milan's TOP Audio show in 2009 that Dan D'Agostino parted ways with Krell, the company he had founded nearly 30 years earlier. Within two years, he had designed a new solid-state amplifier with which to assault the high-end, and launched a new company, Dan D'Agostino Master Audio Systems. The two units reviewed here show careful evolution, retaining a recognisable look while adding to a legacy of fewer than 25 models over 15 years.

It's the power amps that most recall the original Momentum [HFN Jul '11], the new Momentum Z Monoblock (£63,998 each) boasting the now-familiar Breguet wristwatch-inspired meter which dominates the front of its 45kg, 320x130x540mm (whd) chassis. Equally 'signature' are the machined copper heatsinks that form the sides. Placed next to an original Momentum, the resemblance is as close as John and Julian Lennon. The same meter occupies the centre of the C2Z preamp (£65,998), where it doubles as a rotary volume control.

JFET fuelled

Where these amps differ from D'Agostino's earlier Momentum models is their new 'Z' technology, which introduces a JFET-based voltage gain stage [see boxout]. This Z circuitry is retrofittable to the brand's Relentless 800 [HFN Jun '24] and Relentless 1600 power amplifiers, the Relentless Preamplifier, and the original Momentum C2 preamp from 2024. That unit remains on sale but shouldn't be used to drive the new Momentum Z, or any future 'Z-based' D'Agostino amp, in its standard guise.

It should also be noted that the line-level C2Z preamplifier has only one upgrade option. The DSM (Digital Streaming Module), priced £11,998, offers USB-B, optical and coaxial inputs as well as wired/Wi-Fi Ethernet, with files up to 384kHz PCM and DSD256 supported. D'Agostino's DSM app, available only for iOS devices [Note to Dan: Please release an Android version], integrates the Qobuz, Tidal and Spotify streaming platforms. No phono module is available for the C2Z, although as it has three XLR balanced inputs and one RCA single-ended input, and the world is awash with standalone phono stages (and DACs for that matter), it's not too great a loss.

Above: The separate DC supply [see pic, p45] enters underneath the C2Z [top left]. The balanced JFET input, tone control and output PCBs are edge-mounted onto the main board [right] with wired connectors to the XLRs

Connection to the Momentum Z monoblock is via balanced XLR only, D'Agostino including a set of RCA-to-XLR adapters in the amp's accessories box. A fully balanced design, its power rating is 500W/8ohm, doubling thereafter into 4ohm and 2ohm loads [see PM's Lab Report] and delivered by 24 pairs of bipolar output transistors. The amps' footprint and weight will determine location, but the units do run fairly warm so adequate ventilation is a consideration.

Taking the pulse

Rear-panel connections, in addition to the single XLR input, are a 15A IEC mains input, 12V trigger in/out sockets, a pair of spade-only speaker terminals, and an Ethernet port. The last of these is a first for D'Agostino and enables real-time monitoring of the power amp's performance data via a web browser. Useful for both professional installers and owners, this covers operating voltages, temperature, bias, DC offset, 12V trigger status, and other specifications. The 'dashboard' can also be viewed on the company's DSM app.

Built to the same overkill standards as the amps, the two-chassis C2Z comprises the power supply – which acts as a base – and the preamplifier proper. This, too, requires forethought for placement. Combined, it weighs 33.1kg and has a footprint of 432x226x386mm (whd). The upper preamp section must be lowered precisely onto the lower power supply chassis so that the latter's multi-pin connector isn't damaged.

Face value

Our C2Z was supplied sans DSM module, resulting in an uncluttered back panel and making setup a breeze. A 13A IEC 3-pin mains cable enters the lower chassis, where the main on/off switch resides. A small rear-panel aerial provides Bluetooth signalling to the table-top remote [see pic, p49], while the back also has 12V trigger sockets and RS232 system connection.

Among a cluster of buttons to be found on the left of the C2Z's fascia is one for power-up from standby. Source selection, mute and headphone are also accessed by these buttons, while those on the right side, below bass and treble rotary tone controls, operate the digital module, if fitted. It's worth mentioning that inserting a headphone cable into the C2Z's socket, which is nicely protected by a sliding cover to keep out schmutz, doesn't mute the preamplifier's main output. Pressing the headphone button takes care of that, as well as selecting the headphone amp section.

Above: Signature copper 'venturi' heatsinks are machined from 19kg billets, wicking heat from the 12 pairs of bipolar output transistors per side of this balanced/bridged monoblock. Two 1.2kVA toroidal transformers [under the PCBs] support a multi-rail PSU feeding the JFET input and power amp stages. The 'Z switch' is behind the XLR input [left]

The preamp's large circular display indicates gain while a slightly smaller LCD porthole on the power supply mirrors the screen of that multi-function remote control, showing selected input, balance and polarity setting, volume, etc. Meanwhile, the meters on the Momentum Z monoblocks combine a 3.5in LCD with the brand's emblematic analogue wand.

Easy does it
Before the amps made their way to KK [writes Mark Craven], they were put through their paces in the HFN Listening Room [HFN Yearbook '25 & p43]. In truth, the monoblock pair, compact in high-end hi-fi terms, looked small next to Wilson Audio's towering Alexx Vfx floorstanders – yet they were in no way overmatched. The impression of easy-going power was ever present as tracks were played through the dCS Varèse streamer/DAC [HFN Feb '26].

'Dangerously Easy', from Olivia Dean's Messy [PLG/Capitol, 96kHz/24-bit], has a gentle tempo and ostensibly simple arrangement, but there were spatial layers that the Momentum Z amplifiers brought to the fore in an unflashy fashion. Dean was an unrestrained central presence, ahead of her background singers and what sounded like a Fender guitar at the rear-left of the stage. The punch of the bassline and drums was tight, yet the performance retained a lush smoothness.

Rich and powerful

More revealing of the system's lower-octave nous was Alison Krauss and Robert Plant's 'Through The Morning, Through The Night' [Raising Sand; Craft Recordings 96kHz/24-bit]. Here the amps found new depths as they leant into the plump double bass, conveying its weight and texture. Meanwhile, Krauss and Plant's exceptional vocal synergy was rendered with real sweetness and excellent definition.

Indeed, despite the appreciable power of the Momentum Z monoblocks, you don't get the sense that notions of smoothness and 'musicality' have been jettisoned in a quest for outright slam, grip and transparency. If it's richness you're after, these amps oblige. The shimmering percussion and piano on the title track of Don Henley's The End Of Innocence [Geffen 96kHz/24-bit] were balanced by a liquid-like bassline and a sonorous quality to Henley's lyrics of lost youth.

Above: Seen here with the 'Digital Streaming Module' installed (not included on our sample), the C2Z sits on a combined DC PSU and isolation base, offering four line ins (three balanced on XLRs) and two balanced outs. The BT aerial [right] serves the remote [p49]

The amps showed their gutsier side when building the dense soundscapes of the 2013 Mike Oldfield/YORK remix of 'Ommadawn' [Tubular Beats; UMC]. There was impact and weight to the programmed drums, delivered on a scale that proved the amplifiers' speaker-driving credentials. Yet equally beguiling was the voluminous and rich nature of the synths, and the way the music ebbed and flowed across the soundstage. Over to you, Ken…

Cosmic scale

Such was the allure of these amplifiers that I listened to a dozen albums with breaks only for the unavoidable. It turns out that the Zs ('zee' as in 'ZZ Top') love Wilson Audio speakers – I used The WATT Puppys [HFN Sep '24] – while judicious use of the output levels also let me hear the amplifiers through LS3/5As.

My obsession for the wee monitors aside, the latter would limit savouring the full impact of the system. These amps can deliver sheer force, bass extension and (yes, ZZ Top-esque) maximum SPLs. The WATT Puppys valiantly presented the opening drums (kettle/tympani?) of 'Also Sprach Zarathustra' [Selections From 2001: A Space Odyssey; Columbia MQ1067 open-reel tape] with you-are-there levels and scale. The presentation wasn't just impressive – it was near revelatory.

Above: The wired Ethernet port allows access to service data – including operating voltages, temperature, bias, DC offset, 12V trigger status, and more – via a web browser. A balanced XLR in and solid metal binding posts (speaker cable/spades only) set the minimalist tone

Part of the delight came from the sheer quietness and freedom from restraint afforded by a kilowatt into 4ohms. Even the weird 'outer space' sound effects had some sort of veracity, though it's anyone's guess as to what they should sound like. So unimpeded is the power delivery that I couldn't see any movement from either of the Momentum Zs' meters until I turned up the C2Z to levels that horrified me. With nary a hint of break-up or strain, it made me wonder how anyone can live with 3W single-ended triodes.

Bang theory

Reverting to subtlety rather than impact, both Sarah Vaughan (With Clifford Brown) [Supersense 016 mono vinyl] and Carly Simon's Spy [Elektra 1R1 7014 open-reel tape] revealed the system's adroit handling of breathiness and exhalation. Turning to The Bangles' delicious and poignant 'Eternal Flame' from Everything [CBS 462979 1], every nuance in Susanna Hoffs' delivery was communicated with authority but not heavy-handedness.

Bang, bang, bang, album after album: richly textured male vocals from Fink on The Lowswing Sessions [Lowswing LOSW010], and the bizarre Beatles Arias [Polydor 583 702] with Cathy Berberian for operatic interpretations of the Fab Four's hits to hear the liquidity. The big band experience of Sy Oliver & His Orchestra's smooth and silky The Big Sound! [Pickwick P4T-435 open-reel tape] came with room-filling dimensions. Then crystalline guitar from Chet Atkins on The Guitar Genius [RCA Camden CTR753 open-reel tape] and pristine harmonies from The Tokens And The Happenings' Back To Back [BT Puppy BTX 1002 open-reel tape] – and no listener fatigue after nine hours.

Above: The C2Z's alloy/Delrin (BT) remote, with LCD screen, offers control over most functions while mirroring the preamplifier's front panel display

However, the headbanger in me was awakened at the end of Carly Simon's Spy. 'Memorial Day' boasts one of the best drum solos this side of The Sheffield Drum Record [Sheffield Lab, Lab 14], despite the quarter-track, 3¾ips tape. Hearing the stretch of the drumskins, the speed, the splash-sans-unwanted-dampening of cymbals – it showed how power corrupts in audiophile terms. The credo might go, 'It's hard to be satisfied with less'.

Hi-Fi News Verdict

Those familiar with the Momentum series, including the MxV upgrades, will be delighted to discover that D'Agostino has extracted even more refinement while increasing the sense of limitless power. Yes, the brand's Relentless series goes a step further, even if heading in another direction might better satisfy a quest for delicacy. But hear this pre/power system in action and you'll likely want nothing more.

Sound Quality: 90%