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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
guidocorona OP
4,298 posts
 
Hi Fredmiu, while I loved the M725 monos, the performance of M925 is simply of a totally different caliber. M925 combines a an immersive transparency in its harmonic density, an authority that seems to have a natural right to its existance, rather than forcing itself on the user. Yes, M925 has loads more authority, transparency, and detail than M725.... But not in a sterile manner that means detail for sake of audible acrobatics... It is a presentation that gives you much deeper insight into the music: both from the point of view of the music composition/song, and of the depth of the performance/interpretation.

This is a very long topic... PM me if you would like to chat offline.

Guido
psag
518 posts
 
Guido, I have no doubt that its a wonderful-sounding amp. My first high end amp was one of Rowland's Class D offerings. Ultimately I felt the need to let it go, as it lacked the ability to convey (for me) real musical excitement. It took me a long time to realize that something was missing. Since then, I've occasionally read comparable things about other Rowland amps from a few of the more discerning reviewers. At this exalted level, I think it comes down to personal preferences.
fredmiu
4 posts
 
My understanding Class D operation refer to the output stage, aiming at delivering power and dynamics, ability to deal with speedy and transient responses.

Frankly I was not too impressed with the previous 3xx models in class D. Yet the 925 sounds real sexy in the showroom with its ability to drive demanding speaker systems.
fredmiu
4 posts
 
Hi Guido

Many thanks for your comments.

I think I should have more serious listening of 825/925 in the showroom coming months - probably a gift for the New Year.

Cheers, Fred
guidocorona OP
4,298 posts
 
Hi Psag, which Rowland class D amp did you use? G.
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