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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

Showing 2 responses by noble100

noble100's avatar
noble100
2,419 posts
 
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
noble100's avatar
noble100
2,419 posts
 
Guido,

Congratulations. I know you've been looking forward to their arrival for a while. I saw a photo of the 925 amps at the 2012 Hong Kong audio show that I think were prototypes, and they were gold colored. Are yours the same or are they housed in the traditional polished aluminum cases? Either way would look very cool.

Also, are these a similar class A/B design to the 625 amps in that they tend to bias more into class A as they warm up?

Since you live in the warm climate of Houston, I would've thought you'd give serious consideration to buying a pair of high-end class D monoblocks that run almost cool. Two large amps, putting out 850 watts@4ohms and heavily biased into class A, will likely produce copious amounts of heat.

Did you consider any other amps, especially the Merrill Audio Veritas or Mola-Molas?

I'm looking forward to hearing your impressions on these very interesting amps. I'd also like to learn your thoughts on how the 925 amps compare to the other high-end amps on the market that you've heard. But I do realize that it'll probably take a few months for your new amps to break-in and reach their optimal sq.

Enjoy your new amps,
Tim
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