Cartridge break in

IMHO and with LOTS of experience about 40-50 hours.

I agree. Sometimes it takes even longer. I find that it helps to log how many hours you are putting on a new cart. Its easy to loose track.

Varies with the cartridge/compliance material. Don't be surprised if you have to readjust the VTA, along the way.

Thanks.
Just switched from a SoundSmith Zephyr to a Lyra Kleos.
The Kleos has more of audiophile everything: bass, imaging, impact…
But the high end is too edgy for my system and vocals have a papery quality. I'm hoping that this will tame after some hours of break in.
Otherwise back to the Zephyr.
Rest of the system: VPI Aries 3, VPI 3D 10" tonearm, Musical Surroundings Super Nova phono stage, ARC preamp, Bel Canto Ref500 mono amps, Joseph Audio Pulsar speakers.

It varies. Suspensions for different cartridges are made from different materials, some soft, some hard. Different materials don't all wear at the same rate, do they? And, yes, the VTA may change during the process.

Maxh nice system you have. Good luck with the kleos. I have never had any component or cable change that much over time. If I don't like it out of the box I usually don't change, but that's me. I know others have very different experiences. Hope it works out.

Agree with Rodman and Mosin. With regard to Pops' experience, I've experienced both. Some cartridges change wildly in the first 25-100 hours, including basic changes in character - particularly at the frequency extremes. Others barely change at all.

Some suggestions:

Make sure you're cleaning the stylus effectively (ie, Magic Eraser + brushing) after every side

Make sure your LPs are truly clean

Check with VPI to see if they recommend additional headshell weight for the Kleos (they can provide)

Try increasing VTF in .01-.03g increments, listen for some taming of high frequencies

Try lowering arm height by TINY amounts, listen for closer integration of HF harmonics with their lower frequency fundamental

Try changing the phono input impedance, which is adjustable on your Musical Surroundings.

5-6 weeks of play about 40 hours can make some difference. I couldn't wait and recorded an album onto my Nakamichi Dragon right after I got my new Benz S cartridge. A month later I rerecorded it over just because I read about cartridge break in and wanted my recording to be the best. Well I accidently failed to record over first 15 seconds and when I played tape back there was a noticeable difference in the bass from the first 15 seconds. It had tightened up. The song started with bass drums so I didn't have any high frequencies to compare. I hadn't changed the bias or record settings because there had been no other tapes recorded. The only other thing that might could matter is the warm up time on the Dragon. I don't know if it was the same on the 2 recordings. Some Audiogoners could repeat this chance experiment and post their results. The song was Helena Beat by Foster the People.

If your MC cartridge is used and you've just had it re-tipped would it require break-in again?

That would depend on whether the rebuilder replaced the
compliance(the material in which the cantilever is mounted),
or not.

Thanks for the feedback.
I'm pissed with myself because the Aries/Zephyr combo was "dialed in." I was really pleased with the sound: violins had a woody mellowness without a trace of harshness; piano reproduction inched closer to how a piano sounds.
But I wasn't satisfied; more is better; a $3K cartridge must be better than a $1K cartridge.
Oh la…
In fairness to the Kleos, it is better Hi-Fi. It seems clearer and more defined but the result, for me, is a better look into how the recordings were made and not into the enjoyment of music.
I fell like the traitorous Cypher in the Matrix. I don't care if my system is not accurate; I want to be fooled by it.

Unfortunately going up the hifi ladder can be difficult as one upgrade will bring out the next weakness in your system.

The Lyra Kleos is not a bright cartridge, it is very smooth and transparent. Perhaps a little hifi sounding compared to a dynavector and perhaps the SS.
Your musical surroundings phono now has to use an additional gain stage for the mc signal. The ms phono is now your weakness as it can sound mechanical and lean.

You replace the ms phono with something better and the Kleos will start singing.

Tuff decision, as IMO if you want to get the most out of the Kleos you need a better phono stage.

I'm unfamiliar with the Musical Surroundings SuperNova, but in principle I concur with Downunder. An inadequate phono stage can distort the richly detailed but very low level signals produced by really good LOMCs.

There's reasonable debate over the "best" order for upgrading turntable vs. tonearm vs. phono stage. IME, upgrading any of these yields positive results.

OTOH, there's almost no debate (among those with experience) that ALL THREE must be up to snuff before undertaking a major cartridge upgrade.

Disproportionate cartridge upgrades are often disappointing, either because a high end cartridge reveals weaknesses in its support system (TT and arm) or because the phono stage can't cope with the depth of detail.

From my own components... my $8K LOMC sings like a goddess on my main rig and phono stage. She does all the audiophile things but in a coordinated way that makes ravishing, lifelike music. However, she can sound miserable on an entry level rig or feeding a low quality phono. If I'd bought this cartridge before having a suitable TT, arm and phono I might not have been happy.

OTOH, I've tried several inexpensive MMs in my main system and most play way above themselves. A $275 MM can fool people into thinking that it's a $1-2K cartridge.

TT, tonearm and phono stage first. Cartridge upgrades should wait.

DU and DD,
That was my first thought; that the new cartridge had exposed some limitation in the system.
I'll let the Kleos break-in before looking at the most obvious possible sources: the phono stage and/or the preamp.
The Musical Surroundings has been well received in the press and has been a pleasure to use. It has two great assets: it is dead quiet (possibly because it is battery powered) and it has three independently adjustable inputs. I have an old Thorens that I use exclusively to play 78s.
Any suggestions that would work well in the Aries/Kleos combo?

Manley Steelhead: I finally broke down, traded some gear that was idle, and got one and it is so much more refined and detailed than any other I've owned before. Large chunk o' change but the Kleos will definitely thank you for it. Also, Parasounf JC3 or Aesthetix Rhea are candidates from personal experience. Not in the same league as the SH though.