Warm-up time.

It takes about an hour of loud playing for my system to come to life, whether it's digital or analog.
i was wondering if it's the amp or the preamp that needs the warm-up, or both.
i have a vintage modified CJ preamp, and modified NuForce Class D mono blocks.
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I would think that the Class D amps shouldn’t take more than a few minutes to warm up.

If the cj preamp is tube based, they do indeed take awhile to reach full potential.
I agree with mofi,

Probably is your cj especially if tube,I usually leave my class d amps on most of the time so my system is ready at a moments notice,I listen at diff. times of the day.But in general class d amps don't need much warm up time that I have noticed.

I hope this helps you,

Those NuForce amps are very efficient, I would leave them on all the time.

I recently got to listen to an ARC integrated, and about 45 minutes is how long it took. It started out OK, then got really grainy for a while, then came out smooth and sweet.


Everything needs a warm up: Speaker surrounds, phono cartridges, amps, preamps. Every dang thing! 
Including ears and brain.
It takes 2-4 hours for my high-end SS amp and high-end valve CD / DAC system to warm up to hit its peak performance capabilities. It is a very common practice, especially with tubes.

But it does not involve playing it loud, or even playing it all during this start-up ""warm-up" logistics exercise. Rather  just letting it all calmly warm up slowly on its own and actually leaving it alone suffices. 

I'm puzzled by the OP's gear requirement to crank it up as his required modus operandi. 
It takes my rig about 40 minutes to start sounding awesome, an hour gets me where I want to be.  On vinyl, I hear improvement after the 1st side.  After a 2nd side, its pure bliss.  
In your tube component especially, warmup is essential to prime listening. The nodes must be burning for a while before the electrons fly across those gaps in a smooth unwavering flow. Keeping the component on all the time can keep your electric meter spinning as it can generate much heat, depending upon the tube type. But you wouldn't have to remember ahead of time to turn it on.
I've never found the need or noticed any difference in playing music during warm up. I come home, turn it on and putz around and then start playing music awhile later. 

It takes my system about 30-45 minutes before it 'gets going'.  I wonder, though, if just leaving the system powered on does the trick, or if you actually have to be sending signal through for it to make a difference.
I have the same question as parabolic.
The only things I keep powered up are my SS phono-pres.
On some sessions I think I hear an improvement after 20 minutes, on some I notice no change. The ones where I do notice a change are usually playing LPs vs digital sources. And usually with a DL-301 vs a Shure V15.

In my experience it’s 20 minutes of actual playing time for a solid state amp.  So I throw on a CD, leave the room/go about my bidness and when I return the system is ready to pay some sweet sonic dividends.
Contrary to some of what has been said, tube electronics warm up relatively quickly.  CJ and AR both suggest about 30 minutes.  SS stuff can take hours.  The advice to leave SS stuff on all the time, especially if it is not Class A, makes a whole lot of sense.
Perhaps being on your second or third drink is making that "warm up" sound so sweet!
My rig is always on, except for my tubed phone stage and I still need music to run through it to get it going.
Both, solid and hallow state equipment are powered up 24/7 and usually becomes puresex after 60-90 minutes of playing music.
Even staying on contiuously I find my system still appreciates about 40-60 minutes playing before it really starts to gel. 2-3 hrs later it's magnificent... All tube: mono bloc amps, pre, and dac.
Everything needs a warm up: Speaker surrounds, phono cartridges, amps, preamps. Every dang thing! Enter your text ...

The warm-up time of speakers (apart from the run-in time) is rarely mentioned, so nice to see it noticed here. I would say it’s equally important, perhaps even more so than warning up electronics. Prior to any serious listening session (and when the surroundings permit) I often start by turning up the volume significantly beyond my typical reference volume level with some "highly energized" music, and then leave the room for a while to let it "settle in" (half an hour is more than enough). This little treatment can be done, and is necessary I find from the very get-go of turning on the stereo or later on in the process to really have the sound "snap in" and become slightly more present/fuller and alive. Maintaining the lower reference volume level from the beginning seems not to do the same over time, so it’s not really about speeding up a warm-up process rather than having the speakers cross a threshold of sorts with higher levels, that frees the sound increments further. I’ve noticed the same effect with different speakers, so I would assume it to have general importance.

I like to play mine for at least 1 hour before any serious listening, it is all tube based except the DAC.  My speakers are electrostatic (M/L CLX), the claim is that it takes some time to build up a proper charge on the stators, I cannot claim to have experimented to attempt to hear this.

Warm-up is definitely a phenomenon...and I can hear the transition. It's not distinct like going from dark to daylight but it's as much a revelation once you're in-tune to it. Speakers are affected as well. I give up my system for Lent. When I power up Easter morning, I am dejected because it sounds like a big waste of money. I have to remember it's like having a knee-cast removed after 6wks. Everything's stiff as hell. But after a couple days, it's back in the groove and so am I. 
I'm definitely on board the "warm it up" boat. It's strange how the sound becomes more present and liquid once everything is warmed up. Using good old fashioned class AB amplification, it takes some actual listening to get things really warmed up, which thankfully won't be the case when I finish the class A amp. Even leaving the old unit on for a few days makes a difference that's hard to quantify. 
When I had my Atma-Sphere rig, a 1 hour warm-up with no music playing was sufficient (but necessary).  Later on, with an all-Rowland system including a Model 5 power amp, that amp just sounded better and better the longer it was on.  When I was off for the weekend, I would leave it powered up all the time.  It did sound okay after about a 30-45 minute warm-up; the Capri preamp was always on as was the CDP.
My components "warm-up" while I'm listening. Kind of like a "first-set" of music type of thing. Once the first set (1 hr?) is over, it stays on during the between-sets-break (20 min?). Then onto set 2. Most band saves their "best" for the second set anyway, and by the start of the second set everything is warned up. :)