Experiencing Rowland M925 4-chassis reference amps


My pair (or should I call it my quartet?!) of the new SS Rowland M925 reference mono amps were finally delivered yesterday.... Needless to say, I am excited!

The 430W M925 monoblock amplifier is a hefty affair: The amp is formed by four chassis: two power supply chassis and two audio chassis, amounting to a total weight of 380 Lbs in the four boxes, and 320 Lbs in their birthday suits. Each chassis is double boxed, protected by heavy urethane foam inserts, and then bagged in a heavy cloth sleeve tied with a drawstring.

Each power supply box also contains an accessory carton, featuring a power cord terminated at one end with a 20A IEC connector, a heavy ombilical to carry DC current to the audio chassis, and a skinnier ombelical, which I conjecture carries control signals and may have an additional grounding line. A baggie contains 3 1-inch spherical delrin footers that can be screwed into the divets at the bottom of the SMPS chassis if if you do not use 3rd party spikes/footers. A smaller baggie contains 4 smaller delrin beads... They fit into the dimples milled into the top of each the power supply chassis, and are used to keep top and lower chassy from touching when the two are stacked.

I am using Nordost Titanium Sort Kones instead of factory-provided footers. Each power supply chassis stands on top of 3 divet-centered Kones. The whole thing sits on top of 1.5 inch thick granite slabs, which have been patiently waiting in place for the M925 amps since 2011.

The audio chassis are even heavier... They will get into place in the next few days, one way or another. Rowland recommends the stacking be a two-person job.

In order to break-in both output terminal in each unit, I will connect each amp to my Vienna Die Muzik with a form of shotgun wiring: Aural Symphonics Chrono and Cardas Golden Ref for the time being. The Aural Symphonics speaker wire connects to the single 5-way binding post of the Muzik speaker with bananas; the Cardas Golden Ref connects to the same posts with spades... I have already tested the configuration using other mono amps... Works flawlessly. Of course, I have no idea if M925s benefit from shotgun wiring... This will be part of the discovery fun!

The amps will be fed by the Criterion linestage through Aural Symphonics Chrono B2 XLR ICs.

Power cords will be Aural Symphonics Magic Gem and Ultra Cube XXV, plugged into a dedicated 20A circuit served by Furutech outlets.

According to Jeff Rowland, breaking may be excruciatingly long, because of the oversized input transformers and power supply. I suspect that the process may extend well into the summer months... I will log my periodic observations on this thread.

For sake of completion, here are the amps specs as far as I know them:

Monoblock Power Amplifier OUTPUT POWER: 430 watts @ 8 ohms/850 watts @ 4 ohms
Monoblock Power supply: 2400 W regulated DC SMPS per channel, with Active Power Factor Correction (PFC).
FREQUENCY RESPONSE: 5 Hz - 50 kHz
INPUT IMPEDANCE: 40k ohms
THD + NOISE: 0.004%, 20 Hz- 20 kHz
OVERALL GAIN: Switchable 26/32 dB
Combined AMPLIFIER chassis & POWER SUPPLY chassis WEIGHT: 160.4 lb / 73 kg (per channel)
TOTAL DIMENSIONS (H/W/D): 16.5" x 15.5" x 16.25" (per channel) 419mm x 394mm x 413mm

Saluti, Guido
guidocorona
All, yesterday, at approximately 430 hours of playing time plus 60 hours of low-level operations, the M925 amps were showing signs of musical grandness as well
as of some… residual break-in growing pains.

The Dvorak 9th Symphony 2nd movement under Bernstein and the Israel Philharmonic is magnificent: size and clarity of staging, imaging, speed and fullness
of macro transients, authority…. The lower brass fanfares are not only powerful and harmonically complex, but are heard inserted into the living context
of the 3D stage, rather than a musical object without spatial references… I know I said this before, but the reality is that these effects keep growing
in perceived size, complexity, and sheer emotional impact.

The massed upper and mid strings are not only textured and sweet, but resolve into the bowings of the individual fiddles and violas. The flutes have an
ethereal beauty, while the English horn keeps enhancing the multilayered earthiness to its melancholic sound. The chamber-like section toward the end of
the movement is assuming delicacy, detail, harmonic richness, and a filigreed transparency that are enchanting....

However, we may have a little temporary break-in tantrum… The mid bass has lost a bit of power and resolution, while manifesting some signs of wooliness...
I could hear the anomaly in the introduction of the Dvorak sextet with double bass, in the plucked electric bass of Diana Krall’s Temptation, and in a slight
uncertainty of the string bass line of Dvorak’s 9th, particularly the plucked sections... The bass anomaly could also be heard in a certain lack of vicerality
in the midbass of Bach's toccata, adagio and Fugue in C minor performed by Wolfgang Rubsam on Naxos redbook. Interestingly, the minor emotional disorder
does not affect the deep bass: the lowest bass notes in the adagio movement remained visceral, pitched, and harmonically textured.

Today I powered down the whole system including amps, and disconnected all components from the AC for four hours, so to recycle charge on all capacitors, transformers, etc…. I will log my next report at the end of the month, close to the 600 hours mark.

Saluti, Guido
Hi Guido,

I've been following this thread and have been enjoying your good reports. I'm glad you're digging your impressive amps.

The gold appearance of the 925's at the Hong Kong audio show may be as you say, a photographic artifact. It could be a reflection of gold colored curtains or surroundings in the platinum mirror like finish. It looked nice but, if I was investing that much money in a pair of amps, I think I would order the platinum as you did.

So far, it sounds like you made a great choice.
Enjoy,
Tim
Hi Tim, in olden days, Rowland used to offer some amps in a golden livery...In fact, the front plates of my old 7M monos had a warm champagne hue... Nowdays, the only faceplate available is the untinted 'platinum' look, with charcoal Venturi cooling side channels.
Guido:
Your continued impressions on the differences between the 725's and 925's are most appreciated. Thanks and congratulations on your new amps!
Hi Jjy, admittedly, my M725s are wonderful amps, but what I heard tonight on M925 at the 576 hour mark, is simply not possible on M725. I was postponing any serious listening to tomorrow morning (Saturday), so I decided to turn on my old NAD tuner and listen to Film Score Focus on KMFA Austin instead... Today the program was dedicated to "travelling to the Moon" or something to that effect.... The track "The launch" -- by James Horner I believe -- from the 1995 film "Apollo 13" blew my mind for the intimate depth and power of the bass.... Not a bloated swelling thing, but a tidal depth at the very bottom of the audible range.... Something that the triple 9" bass drivers of the Muzik speakers were transmitting to my chest and feet perhaps more than to my ears. The entire image: bass, and mostly synthetic orchestra occupied a solid continuum from beyond the left wall to beyond the right wall. Mesmerizing is perhaps the best way to describe it... Sure, there was authority and all of that, but.... An authority that just "exists" without the need of questioning its right to be... An authority that works for the music material without attracting attention to itself.... Just allowing the material to flow in a totally integrated way, because.... It is in the nature of music to achieve that... And in the nature of the amps to deliver the effortless magic.

I realize that this is rambling and all, but tonight I do not have a better way to express it.

Tomorrow I will play once again my usual test tracks... But I have a strong hunch that the bass malaise that I reported last week has gone away.

By the way JJY, do you own Rowland M725 monos?

Best, Guido