Break in time that extends to months or maybe even years!!

I concur with @almarg, @hilde45, and @zavato… Control of independent variables is of the utmost importance in the review process, and should be implemented as much as possible to achieve reasonably meaningful findings.

In a perfect world, twin copies of the target component or cable should be used for periodic comparisons of performance throughout the break-in process… One copy being the full break-in target, and the second one as a control with “low mileage”. Now suddenly, I hit myself, because I just realized that I had a perfect opportunity to do that when I examined the Rowland M535 bridged a spell ago… I should have started in stereo mode, and used one of the two units as a low mileage control, instead of breaking-in the pair as a bridged set. Oh well, next time I evaluate a bridgeable amp, I’ll apply this technique for sure.

Would be nice to track voltages, air temperature, and humidity… Next time I am born I’ll make sure I stay fully sighted, so I can read measuring equipment… Oh well *Grins!*

On the other hand, I do control the test environment as much as possible, as follows:

• I maintain system configuration to be invariant during each individual evaluation phase. This means that all components remain the same; cabling remains the same; usage of AC outlets remains the same; no equipment has moved around stands; layout of cabling on the floor remains the same; no furniture has been moved, orientation of window treatments remains the same.

• All ancillary equipment is already well stabilized: In my case, all equipment has been with me between two years (cabling) and 14 years (CD transport)… I was forgetting equipment support benches (60 years).

• Break-in process continues 24/7, except for power-off time during thunderstorms and for discharging capacitors (did this twice). Did any critical listening at least several hours after the last power-up… More typically, days or weeks after.

• I make consistent use of review material… A test CD contains the same sampling of music tracks that I have used for evaluating equipment at home, at shows, and at stores for the last 15 years… In addition, I use several other CDs representative of music genres of interest to me.

• While I listen to entire CDs during critical listening, I do concentrate on particular passages that I have known to expose possible flaws or merits in a review target: harshness from intermodulative artifacts, pillowing/unspecific bass, harmonic exposure changes in broad treble to bass arpeggios, transient clarity vs opaqueness, decay complexity, staging/imaging changes, very low level information, ambient noises, performers’ subvocalizations.

• I document observations in contemporaneous notes also logging dates and break-in hours, which when cleaned up form the basis for diary posts, and in an ancient past, I have integrated into published reviews.

• Use a break-in tracker spreadsheet… This maintains break-in status for each day, hours of operation each day, start time, power down time, total hours count since beginning of project, and completion date projections.

•       At the end of each project phase, for instance use of an integrated as a complete integrated, I make minimal changes to start the next phase, which might be for example feeding the linelevel signal from the linestage of the integrated into my reference monoblocks… I will use for this the same pair of well broken in XLR ICs that I have been using for the last two years from my reference DAC to the monos.

•   I will run this configuration for at least a couple days before any new critical listening, and will use the same tracks and passages that I used on the integrated. I will probably need to go back and forth between full integrated and its linestage subsystem into the monos to derive a reasonable assessment of the difference. Yes I know, the reintroduction of an IC will somewhat smear the results.

• * I would then use the same XLR ICS when I test the output of my reference DAC into the integrated linestage + amplification subsystem.  

As you might imagine, I can’t examine dozens or even a handful of components a year this way: It is a very time-consuming process. Never the less, it is for me a happy labor of love which I enjoy sharing with fellow lovers of music and sound… Others may feel otherwise.

Regards, G.

Hello @DaveyF, you are correct, I would not want ever to evaluate a strict monoblock amp by breaking-in each chassis on split timelines... Evaluating mono operation chassis by chassis is a pointless exercise.

The Rowland M535 I was talking about is instead a bridgeable pair... In that a single M535 chassis can be deployed as a stereo amp, or two of them can be advantageously used in bridged mode as a mono pair.

When I received the M535 pair I deployed them as a bridged/m mono pair from the get go, and crossed sonic/musical stabilization around the 800 hours mark

What I should have done instead is:

Break-in the bridged pair for the first 24 or 48 hours.

* Split the pair; put chassis 1 aside; reconfigure chassis 1 and 2 for stereo operation and continue break-in of chassis 2.

At some fixed checkpoints, e.g. 100 hours mark, 200 hours, 350 hours, 500 hours, 650 hours, and 800 hours mark, compare the stereo performance of chassis 2 with chassis 1 which would have been still a juvenile. Any differences? Document each checkpoint with copious notes.

At the end, set aside chassis 2, and complete break-in of chassis 1 in stereo mode to 800 hours.

Reconfigure the two units for bridged operation. Reconnect the whole and play for a few days. Take notes and document tonal/resolution/etc... differences of bridged pair from single chassis in stereo mode.

You still with me after all this time? No worries, the fun is not over...

Power down and disconnect from the wall outlet. Disconnect speaker wires from the bridged output terminal of each chassis. Slip the optional external networks onto the mono terminals of each unit. Reconnect speaker wires. Plug the units into the AC, and play music.... You might notice a further positive delta, which to my experience continued to open up further, plateauing after about 100 hours.

BTW, the slip-on networks are free for the asking from the factory... Yes, I know, it would be nice if they were inside the machines... No, not possible, because the designer thought of enhancement about one year after release... No he could not retrofit the design, would have required a semimajor chassis machining / board / wiring change.

PS, Do not slip the networks on a M535 unit in stereo mode, nor try them on any device that is not an M535... You would slag the device with a nice Pop! Possible sparkles, pretty curls of blue smoke, and cute scent of singed electronics... And you'd void any warranty to boot. Yes, Rowland includes a card warning against improper networks use with these add-ons.

Saluti, G.