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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
chazzzy007
540 posts
 
@guidocorona 

Thank you for the response. 
I follow and post on WCSS's thread,  but he had his 925's less than 3 weeks before he sold them. His descriptions and comparisons were fairly brief. 
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astewart8944
499 posts
 
@chazzy007 I share your dampened enthusiasm concerning whitecamaross' methodology on short term amp listening and then resulting public proclamations. Like Guido, @guidocorona, I own the M925s. I have been running them for about a year with the Rowland Corus/Aeris/PSU combo. I use Cardas CB XL PCs for the M925s. Otherwise, I have a full Cardas CB loom. I share Guido's enthusiasm for these amplifiers. I'm confident that they need the 1500 hours of break-in Guido recommends. I went on this wild ride personally--the first 24-48 hours were really good, then the M925s got brittle--so much so I PM'd Guido and had him give me encouragement. And the ups and downs lasted a long time--but every time they seemed to plateau, then go down then sidesways, then reach a higher dimensional plateau. This continued for about 6 weeks. I'm surprised whitecamaross did not have this experience--it seems to be fairly common. Anyway, Guido's descriptions of break-in are, frankly, spot on. He truly knows and describes Jeff Rowland gear very accurately. I can't help you with meaningful comparisons between side by side M925s and other amps. But some listening history may help you. I have owned the JR Continuum S2 (which whitecamaross would love apparently since he is currently doing integrateds now). I have heard the JR 625S2 on multiple occasions. I have also heard the Daemon Integrated twice at AXPONA last year and this year. And I have heard other M925s besides mine at a dealer recently driving Magico speakers. I can easily state that IMO the M925s perform at a level worthy of being Jeff Rowland's flagship. Admittedly, I really like the JR sound--if it indeed has one--some have said it is the absence of having a "sound" that makes the current products special. The recent models I have heard all provide excellent SQ. But, nothing else in the JR amp line-up I have heard is as effortless as the M925s in providing power with headroom aplenty and a deep black background. Very, very quiet. And very very cool--it is hard to believe that these big audio blocks are always cool to the touch, even when driving highly dynamic music. Simply put, unless you absolutely need 500W or more at 8 ohms into your speakers, I doubt you are going to find amps that will exceed what M925s can offer. IMO this includes the currently hot Swiss and German makers. I'm not criticizing them. I'm saying the JR M925s are on par--or better.
Regards
Al 
guidocorona OP
4,298 posts
 

Thank you so much @Alstewart... You summerized my own M925 experience to a T!


The reason why M925 monos never get really hot to the touch is that they have an efficiency of approximately 93%.


Ther power is approximately 430W into 4 Ohms, reaching 850W into 4 Ohms. Their 2500W DC power supplies let them generate a peak current of 45A per chassis. I never heard them breaking a swet on my Vienna Die Muzik speaker, even with the extremely high dynamics of Mahler symphonies at high SPL.  


The M925 have achieved recently a new quantum plateau in my system. I have adopted a full loom of Cardas cables in my system.... I started with the new flagship Clear Beyond XL power cords, and so to leave still room for future upgrades, the Clear entry level Reflection for XLR and speaker wires.... The result still stuns me: there is definitely a magic synergy between Rowland and Cardas, because I have never heard my system as refined and immersive as it is now.


Interestingly, the break-in process for Cardas wires appears to be quite benign.... About 300 hours likely takes the entire loom to over 90% of their performance potential.... Even from the first few hours one can tell that there is something truly special goiong on..... Of course, there is a bit of performance fluctuation for the first 70 or so hours, after which the performance arrow points steadily up. Did I mention that bass is spectacular and harmonic development is to die for? And I have heard sweetness of treble that I do not believe that any other wires have yielded until now.


Yes, I have loved my M925 monos since 2013 and have never suffered of an audiophilic wandering eye about them... But with the addition of the Cardas loom, these amps have achieved peaks of musical beauty that even I did not believe possible.


I am working on a detailed review of the Cardas loom in the context of my system.... I am still gathering some technical information.... I'll post the full review to Audiogon as soon as it is ready.


Saluti, Guido







 

   




  

  

biggy79
64 posts
 
Hi @guidocorona 
I wait for your Cardas cables review, I suppose in the Cables section.

Very curious about the new C.Beyond XL Power (vs C.Beyond Power, I never fell in love with) but also Clear Reflection Speaker (vs Golden Reference; I need 2 pairs for shotgun and Clear Speaker would be too expensive).
I know well the C.Reflection XLR, I replaced it with the superb C.Beyond XLR because the former sounded too fat in the midbass in my system and room, while the Clear XLR was "too neutral" (thin, washed out, lacking of bass energy).

@astewart8944 in the Cables section wrote the Beyond XL sounds with more detail in the high frequencies but less listening fatigue than the "etched" (I agree) Beyond (I prefer Clear Power on the digital source), and also with tighter bass and expecially midbass...
I did not understand if these changes affect tonal balance, pushing it towards "too much neutrality" (like Clear XLR interconnects) losing bass impact (I would not expect this from an "heavy gauge' power cord).

Many thanks
chazzzy007
540 posts
 
Much thanks to Al and Guido for the comments on the 925. Guido I find your insights and commentary quite comprehensive. Thank you! 👍
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