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).
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
At 150 hours of operation plus 50 hours on low level standby – The undue ringing (I cannot call it steeliness any longer) is barely detectable on a couple
of notes only…. E.g. The closing note of the motet…. Images are continuing the fleshing-out process, and traces of acoustics from the recording venue (a
small Church in Venice( is starting to emerge. The portatif organ used for accompaniment is impressively crisp and deep…. The overall effect is starting
to be musically immersive and “rather wonderful” (quoted words of my better half, who tends to be merciless when commenting about the sound of my system).

On an non auditory matter, the amps take 12 to 24 hours to stabilize thermically, and so become warm to the touch…. During hot days they feel rather
toasty, if not as much as M725 or M625. Temperature seems completely uniform on each chassis... But power supply chassis are noticeably warmer than audio

Saluti, Guido
A non-musical tidbit....

* Unlike M725 and M625, which have a mild propensity to emitting audible rasberries -- of a very high-end cultivar of course -- through the speakers, whenever power is cycled on/off, M925 are extremely quiet. When the front-mounted momentary contact switch is operated to turn the amps to full power, I can hear only the internal "Klump" from a relay switch, folloed after a second or two by an almost inaudible "tick" from the speakers. When the power button is operate again to place the amps back on standby, there is no noise at all from the speakers or from the amps.

Saluti, G.
Time for a few updates… First of all, I have been asked about the audible difference between the M725 330W monoblocks that have been my reference amp for one year, and my new M925…

As much as I love M725, M925 are already generating sound that is in an entirely different league…

First of all the obvious…. That is the M925’s sheer power, which lets them generate life-sized stage and images… Yes, significantly larger and more solid than M725, with incredible ease and authority. There is a sense of space, air, and depth that comfortably exceeds M725, and any other amp that has been in my system until now. M925 never breaks a sweat on high dynamic transients… It is in that totally effortless…. There is a harmonic coherence and exposure of fine detail that is very highly resolving, but is musical rather than being “hiFiish”…. Because it makes music emotional, and never analytic. In addition, the bass has a depth and musical purity to die for. Neither fat overhang nor thuddy behavior here.

Of course, break in is very much still in progress, and we are not out of the woods by any stretch... At 250 hours, I listened to Christiane Jaccottet on harpsichord playing Bach’s Well tempered Klavier… there was a very faint zing added to the upper harmonics of the harpsichord… But this sounded more curious than annoying…. Very different from the typical harshness found in many new amps. What I find astonishing is that whatever fabulous behavior I hear from M925 at any particular session, it is usually exceeded by what the amps demonstrate after another few days….

On a more positive note, I played the Rachmaninov Symphonic Dances in the version for two pianos… A performance by EMANUEL AX and YEFIM BRONFMAN on SONY redbook, recorded in 1999 in 24-bits. Several things were remarkable, and already let me confirm that I comfortably prefer the total performance of M925 over every other amp I have had in my system, including Rowland M725 monos…

• The apparent total coherence and extension of the M925 frequency bandwidth, from the bottom notes to the top octaves, without any perceivable suckouts or fatness/overhangs.
• The fine exposure of harmonic information from the high treble to the lowest bass.
• The vast size/proportions of stage and instrument images, that where completely congruent in the three dimensions with real life grand pianos in a recording studio, with the front of the instrument image approximately coinciding with the front of the speakers, and the left/right edges of the stage merging into the side walls of the room (speakers are 11 feet apart, while the room is 18 feet wide)… This among other things means that M925 is thankfully not a forward
sounding amp, but is also far from being recessed.
• Tremendous macro authority and dynamics, perfectly consistent with the illusion of a pair of real life concert grands in the room, from whispering pianissimo (ppp) to fortissimo (fff) without any clipping or other signs of strain.
• Subtlety of microdynamics, which exposes the sudden partial dampening of a piano string when a key is half-lifted and so, lowers the felt damper to graze the string.
• The instant speed of macro and micro transient response at all frequencies. There is no euphonic caramelization of transients, neither there is artificial emphasis of leading edges.
• The sense of emotion and musical immersion…. The listening experience is relaxed…. I sink into the listening couch and enjoy …. I do not feel the need to balance on the edge of the seat ready to bolt with audiophilic anxiety.

A minor milestone tonight... I have just clocked 302 hours of playing time, and an additional 60 hours of low power ops. I decided to check again the Christiane Jaccottet recording of Bach's Well Tempered Klavier... Disk 2 of 4, to be specific.... The trace burr or overpressure in the high treble region of the harmonics that I reported around the 250 hours mark has disappeared completely. If I did
not know better, I would be tempted to say that the amps have reached maturity, as the sound of the harpsichord was magnificent and musically involving...
But I know I should expect even further opening up... probably intermixed by a few more episodes of minor "bad attitude".

Saluti, Guido
To Noble100... Hi Tim, concerning amp colors, I checked with Brandon Kelley at the Rowland factory yesterday about colors for M925 amps: seems to be a little like the old Ford Model T... Any faceplate color is available, provided it is... 'platinum'... Which is actually natural polished Aluminum color. I suspect that the golden color of the units in the 2012 pics you have seen were either one-ofs, or photograpic artifact.

Saluti, G.