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
Lastly, I have been away for one full week.... Break-in has resumed tonight at the 600 hours mark... The sound has an eary beauty even with the amps stone cold after 9 days completely disconnected from the AC. I listened to a couple movements from Mahler's 4th Symphony conducted by Bernard Heitink... Totally enchanting... Even though from my old NAD FM tuner, the bass was foundational and pitched as clear as a bell.

Guido
Hi Guido, regarding your "beloved" NAD tuner, i am in the market for a tuner but
i don't know if i should spend $150, $1500, or $3500. You seem to be happy as long as the device brings in stations fairly well with as little fuss as possible (i.e. oscilloscopes and other cute add-ons). OTOH Magnum Dynalab makes really great tuners- who wouldn't want an MD-109 if they could win it in a local drawing..? I have a good classical station with a strong signal and very little noise from nearby broadcasts, Plus two stations with good jazz programming.
any thoughts while you listen to your $100 tuner through your $60K amplifiers?
Hi French_Fries, the primary duty of my tuner is to feed FM interstation pink noise hash to the amps. Secondary duty is to let me enjoy the musicology lectures of Bill McLaughlyn... Quality of sound is suboptimal for the rest of the system. But I still enjoy the experience. As of today, I have no immediate plans to replace the little NAD tuner... But who know what the future may bring!

Guido
Mr. G, maybe i misunderstood, but you said you were listening to Mahler through the tuner...? and you stated you enjoyed the experience. But anyway,
i am trying to figure out if a Sansui tuner would be sufficient, or do i need a truly great component (and spend 3X as much)?
I did enjoy the experience immensely French_Fries.... It was in fact remarkable that the bass was so clear, and the voicing of various instruments so distinct, in spite of the ancient vintage of the darling tuner. On the other hand, I am not implying that what I heard was close to what the system is capable of when playing back a top notch CD on the X-01 player.

I should like to point out that with amps that graced my system prior to M925, results on tuner were less satisfying.

I am not an expert in tuners at all, so I really cannot make any meaningful recommendations.