Does EVERY component need break-in?

I just bought a transport new (Theta Carmen). Do transports need break-in as well as cables, speakers, amps, etc.?
Generally there are two camps - the believers and the non-believers.

The believers will probably tell you that it does need to break in.

I have no idea if it needs to break in or not. I can say that if you are not satisfied with any electronic component after about two weeks of use then odds are high that you will never be happy with it. There are exceptions of course but take it for what it's worth.
I have been wondering the same thing. I definitely have experienced changes in cables and speakers after break-in, but don't know for sure regarding amps. It seems like 200 hours or so changes everything, and I'm not talking about my ears adjusting. Even when I let a product break-in without critically listening for a while, I notice many differences, mostly positive.
I am a break-in type and agree with Aragain. Digital seem to take an inordinant amount of time to break in, but 2 weeks of use should tell you what you've got. A transport is a mechanical device with moving parts, and should benefit from a break-in period.
It varies from component to component. I have no doubt about cables and power cords changing their sound for the better after 100-200 hours, and certainly the same with speakers. Amps seem to need less, preamps even less than that; as to transports, anyone who has ever had a Sony SCD-1 knows that after 400-500 hours, it still seems to be improving.
Every component that does not sound good to you right away needs breaking in.

I think that the concept of break-in time is a post-sale customer relations tool used in the retail trade. The non-believers say that after a while your ears should adjust to the character of the new component and it will sound better. (I am an agnostic in these matters.)

I've never noticed a difference with cd players, amps, preamps or interconnects. Speakers, obviously, speaker cables too, but not a long time.
I do it. My new ARCAM CD 92 sounded "OK" right out of the box but it wasn't as "full" and "warm" as I remembered it in the store. This weekend I put it on "repeat" for 36 straight hours and it sounded "fuller" and "warmer", the traits that attracted me to the unit. Ditto for my cables - interconnects and speakers. They sounded better after at least 48 hours of "burning". Good luck.
I feel that most everything changes with break in. Part of this could also be (in this case) from just having the unit powered up continuously for 3-4 days. I recently finished breaking in a Bel Canto DAC after it received the 1.1 upgrade and the sound fleshed and smoothed out considerably with 200+ hours of playing time (which exceeds it being powered up for 3-4 days), but I assume that both were contributing factors. As far as moving parts go, self lubricating bearings do operate more smoothly with use (which will cut down on vibration). I discovered this the first time as a kid when I made slot car frames and motors from scratch and raced them in competition. I just leave stuff on, use it and then hope for the best. I have never heard anything actually sound worse with break in with the exception of a Leviton Pro wall outlet that just got thinner and thinner in the midrange with use (I replaced it with an inexpensive P&S outlet which sounds much better overall plus has a much tighter grip on the plugs).
YES, Leave it on or in stand-by for at least a week before passing judgement.
Unplug your gear for a week, then plug it back in. Thin sounding? Absolutely. Give it several hours, and magically your system sounds just like it did a week ago. I've done this when I've travelled for extended periods of time, and also noticed the same effect when inserting a "new" piece of gear in my system (shipping time is generally over a week). Even used items need time to settle in and perform as expected. This may not be the technical diatribe some would hope for to prove that break-in is necessary but it certainly is easy enough to try for yourself. Unplug everything, wait a week or so, plug it back in. Proof is in the pudding. Jeff
Jeff L. I think that you're referring to "component warmup" vs. breakin phenomenon. Although this is more of a solid state issue, even tubed equipment containing solid state voltage regulators needs to be kept warm. It takes about 30 hours for the regulators to attain thermal stabilization, which is when things seem to sound best at our house. I only power down the rig for lightning storms, or for an extended vacation. I do turn off my amps on very hot days (although wish I didn't have to) because it makes a big difference in the A/C bill