Where's the trade off?

I wouldn't let tube usage stop me from listening ever. They're SUPPOSED to be disposable! The way I look at warm up time is: even cold it's likely damn good sounding. After an hour it's magical and after a few hours downright beguiling. I'm talking about a Dynaco ST-70, with a pair of Dahlquist DQ-10's; as much as I like this system, it's nothing fancy, and I'd bet your system sounds much, much better. I'd just get depressed even trying to quantify how much better I bet your system sounds- enjoy it. If you're determined to make a change amp-wise though, I've had both NAD and Luxman. Nothing against NAD- it was better than I expected it to be, and if it was all I had I'd be totally content. I still have Luxman- and when I hook it up- I LOVE it. Every time.

I think I hear differences with warmup but its always hard to determine these cause/effect type things conclusively.

I think I hear warmup having a bigger effect with my SS gear (which is less problematic to keep on during idle time as well luckily) than I do with my tube gear. Tubes seem to "warm up" faster. Good thing too! Quality tubes for hi fi audio are EXPENSIVE already these days and will probably only become more so over time.

Turn that thing off when you're not around, you wasteful boneheads! I think the "warm up myth" has ensnared too many at this point, and lends credence to the question: Do you listen to your gear or the music? If everybody tells you their gear heap sounds better after being left on for 37 hours, you tend to jump on that boat...and as we all know, no serious gear head EVER turns their AC wasting precious pile off. Unless it's tubes where somehow the Tube Head gets a pass. I not only pass on this, I turn off that road entirely. Example: I keep my phono preamp off all the time (except when it's pressed into service) as it presents an otherwise unnecessary signal to the inputs, that bugs me, and it's my personal cross to bear. The other day I HAD to listen to Lowell George's solo LP and although my pre was only on for exactly 18 seconds prior to the needle dropping, I enjoyed the living crap out of the LP. Would it have sounded better with electrons running around the phono pre for the geek designated appropriate warm up period? Maybe a tiny bit, maybe not so much that any sane person would wait for it...but so what...would I have enjoyed my hero, Old Dead Lowell, more? No. My tube amp sounds great all the time (as does the SS stuff in front if it), from turn on to turn off, and the degree to which any of this may sound better from warm up is far less than the effect of my ever changing mood, ear wax buildup, ambient humidity, the sequins on my cowboy shirt, my rock hard pecs, and the sound reflected off the back of the butler I use as a footstool. I say "tune in, turn off, drop out."

I remember when I first brought home my Rogue. Everyone told me to let it warm up first (and I think the manual says that too) but of course my wife and I couldn't wait so about 3 minutes after I turned it on I turned up the volume. It was seriously very disappointing, but after another 20 minutes of listening I was practically in tears. That's why I normally wait 20 minutes before I begin playing music.

I'm not used to have to wait very long for a tube amp to start making music. I start the system up first thing when I get home and within 30 seconds its sounding fine.

There are things that can cause a longer warmup time, like bad filter caps. Any chance the amp just needs service??