Break-in of a Class D amp?

I'll spare everyone the "brand tribe" debate, and keep my question/details generic.

I recently had to have my 2ch ClassD amp "serviced" by the manufacturer.  Yes, it's an ICEPower derived unit.  I'd been SUPER happy with it for well over 18 months, until one morning when I heard a buzzing coming from inside the amp itself.  I took a video, poked the manufacturer, and they voluntarily opted to fix it for me.

Fast forward a week, and the amp is back in my stack.  But something is amiss. 

I can tell they wholesale replaced the entire ICE module, as the "power up" delay from standby is "different" than before, and it seems to exhibit less overall "gain" than prior to repair.

But the most disturbing thing, and one that literally smacked me in the face... was the lack of high frequency authority.  While there is a soundstage, and lows are not an issue... it's missing all the "presence" and "life" in the top end.  I have tracks that I can play that elicit EMOTION when I queue them.  All the detail and fidelity is like, muted.

The previous board had hundreds of hours of time to burn in, and boy I exercised it.  Is this what I'm now encountering?  Or has anyone out there experienced this situation?  

I would normally just knuckle down and "grind out" hours of "work" for the amp... and not come here asking for advice... but the fidelity difference is so striking... that I can't get over it.

PS Audio had a video recently commenting about burn in time. The number of amps returned to them significantly dropped when the burn in time was increased. Maybe give it some time? 
I recently bought a Class D (Pascal) stereo amp and the owner for the company told me he did not think the amp needed any burn-in. I think he may have been correct since I have not notice a change in the sound (brand new build). My Benchmark AHB2 amp did not need any burn-in either. 

All other gear I have owned sounded considerably better with burn-in.
Sounds like they fixed a problem with a hyped top end to me. In any case I have never heard any component go from rolled off to extended during burn-in. Always the other way around as the high frequency grain and etch that masquerades as detail becomes more liquid natural with time.
Thanks for the feedback, everyone (pun intended).

I guess I'll keep at my burn-in over the next week or so, and if it's not improved... it goes back in the box, and into storage or something.

I've always lusted after blue VU meters.  Maybe it's time to chase some down.
Call the manufacturer and tell them what you are hearing, they might be able to explain it. 
Yeah, I thought about sending a note to the mfgr.  But having worked in the industry on the sales/consulting side in my earlier days... I can't rule out that something in the past week has not changed.  My streaming/dac just processed a firmware update, the weather has changed here in "Cheddar Land", and maybe my ears are clogged... 

There are too many variables to discount, before I start pointing fingers at a brand new (and supposedly certified) amp.  As a vendor/retailer, I'd be suspect of my situation, before I'd be suspect of the amp.

I'm grateful the mfgr did the repair... cause "letting the smoke out" would have been worse.  I don't want to be "that guy".  
The first thing I would do is contact the repair person and ask if they replaces the module with the same type? With a different startup delay and sound, I'd be asking a question or two.. You have nothing to loose and maybe a discount on a second module.  If they don't sound or work the same way, that's really not in the best interest of ANY stereo system.

It's not fixed... BUT it will work.. I've had to FIX a lot of those repairs in my life. We have a different term for it though.. It's called 1/2 A$$ed.
BUT you have a working system making sound. Certainly better off than you were AND maybe the guy didn't know there would be a difference.

I don't think there was anything malicious, just uninformed.. AND he sure can't fix what he doesn't know about, AY?

Those Blue meters can be spendy. I've owned the MC601s and 1.2s.

My back is hurting thinking about them.. I have vintage Mac gear.. Valve gear.. They are heavy too.. Not Class Ds, where you have to ADD weight.. LOL
So indeed it is the same board.  ICEPower 1200AS2.  Comparing pictures, the only REAL difference, is the AC transformer has more "vibration isolation goo" packed between the windings and the core/cage.

I'm positive this was just a "board swap".  No harm, no foul.

And yeah... MC601's yada... Maybe an MC302 cause I don't need TONS of power/reserve for my particular speakers.  But indeed.  Heavy.  :)
To answer your original question, my ICEPower class D amps took quite a few hours to break in.  I wouldn't say they gained detail but more like the highs smoothed and got clearer, so detail was more distinct. 
@tmcclintock Yeah, I'm guessing something is different here.  After 24 hours of burn in (yes I know, a very short period of time), I'm starting to pick up new details.  

While the high's are still not as pronounced, the bass is significantly more pronounced.  I have GoldenEar Triton 2+'s and had to dial the subwoofer gain down to almost nothing.  While I like some "pronounced lows"... this is obscene.

I had to turn off the system after only 3 partial tracks.  It's not enjoyable.  Time to dig around in the couch cushions for some extra change.

Thanks for all the advice folks.
So indeed it is the same board. ICEPower 1200AS2. Comparing pictures, the only REAL difference, is the AC transformer has more "vibration isolation goo" packed between the windings and the core/cage.
While the high's are still not as pronounced, the bass is significantly more pronounced.

Strange all should be the same with just a mains trany change, unless some small damage was done to both channels of the Class-D board which limits the HF and gives the impression the bass is up.

By any chance did you listen to one of your other amps while this was getting repaired?

Cheers George

@georgehihi The entire ICEPower board was replaced... not just the noisy cap.  Same chassis, new board.
Ok, but you said this
So indeed it is the same board. ICEPower 1200AS2.

If it was replaced you either got a dud or a new version with more hf  filtering. 

Cheers George
So after trying to listen to the amp last night, and giving up after just three tracks, I took a note from @russ69 and sent the mfgr an e-mail.

They confirmed what I noticed regarding the "goo", and suggested I keep going with the break-in:

Hello Richard,

Our tech thinks 100-150 hours should do it for break-in.


The only thing that has changed on these ICE modules, is that the replacements have more epoxy on the power transformer to help lower mechanical noise. We are not aware of any other changes.

Was at least 100 hrs for mine and probably more like 200, although part of that may have been breaking in my ears to the quieter background and more clarity at the extremes.  Sort of made the upper midrange seem shallower at first.  Did you listen to a different amp while yours was being repaired?
@tmcclintock Negative.  I went cold turkey for a week.  Kinda made me really appreciate how much I do need/love my setup.

Well... done with work for the day.  Time to "exercise" the amp a bit... and get some more burn-in done.
My experience, and it is shared, is that ICEpower ASP modules don't like to be left off for more than overnight.

Leave them on for about 4 days and they'll recover.


So as a follow-up to all this discussion, I'll leave some notes.

1)  Need for burn-in of the ICEPower boards = True.

I spent a few more weeks with the newly refab'd unit, and indeed it DID improve.  So much so, that I almost hesitated with point #2 below.

2)  The incremental difference between an ICEPower based Class-D amp, and a McIntosh MC-312 was much more significant than I expected.

While stewing with the "newly refurbished" amp, trying to break it in... I contacted my local dealer.  I requested an A/B between MY ICEPower unit (not one he'd had on his showroom floor) and a MC-312 using the same system.

While doing the demo with a few of my select demo tracks in hand, I immediately could sense an enhanced "decay" in some instruments, and for some reason, even MORE separation ... compared to my amp.

So Fast Forward a few months of waiting in line for my dealer to get a drop shipment from Binghamton... and a couple more months of critical listening... and I do admit... "you do know where that money went".

(could not help the movie quote...)
I don’t think a forum can answer your question.  Give it some time and see.  Whoever did the fix should be able to tell you exactly what was done. 
Excellent choice, rabbottmke. I predict that you’ll be very happy with the MC-312. Enjoy.