Long-Term Amp Storage Without Use: Bad Idea???

Hi All.  I've got a nice set of Cary EL-34 tube monoblocks which I haven't used for 2 years.  I put them up for sale, but then decided I'd rather hold on to them for a later day.  That later day could be years from now, maybe even a decade.  I don't expect to pull them out and "exercise" them to keep them in shape.  Is this a bad idea?  I've heard capacitors tend to dry out if left unplayed for too long. Thanks in advance to those who have knowledge in this area. 
Electrolytics tend to dry out no matter what.

I am in the Marie Kondo world view of gear. Use it or sell it, don't store it.
 I know what you mean Eric… But they are kind of rare and all tricked out! 
I would let them work from time to time, it's gamble, anyway.
But they are kind of rare and all tricked out!

Well, that's just what you want to keep in storage. :)

Seriously though, simplify and minimize and it will help you focus on your goals.

Be well,

I would just store them.  When you do plan to use them, it would be best to slowly bring them back to life using a variac (this allows the capacitors to slowly "reform").  If you hear noise, particularly hum, after the amps are up and running, it is most likely some power supply electrolytic capacitors have dried out and need replacement; any competent technician can do that, and if the amps are valuable, that would be a small price to pay.

I suppose "long-term" i s not really a precise term, but, I've heard many amps that were not used for more than 30 years that work perfectly today, even without capacitor changes.  A friend recently bought an amp that is probably 65 years old that is in perfect working order and sounds great; it has all original parts, but I don't think that he knows how long it had been stored before he bought it (I would guess quite a bit of time because the tubes are ancient).
Listen to the dude Eric as he knows everything about everything WOW!!!
There's a really good chance that 10 years from now there will be better amps and better parts with which to trick them out.
If you really plan to not use it that long, just sell it and buy a functioning amp 10 years from now. 10 years is a very long time for filter capacitors to sit without a charge! You'd be better off keeping it in service.
A friend of mine just lent me a pair of Canary CA-309 valve monoblocks with matching monoblock valve preamp. He stored them in original boxes taped shut in his garage in the topics for about 12 years. They are internally rusted to buggery and don't work. A crying shame given what they were worth new. Now I have to work out whether it is worth spending thousands getting them working and cleaned up.
Not that this is a recommendation but my current Proceed HPA2 (Levinson) amp was stored in a damp (really damp) basement for over 3 years (not my doing). There is a trace of rust on the screws that hold the handles on the back. Everything else looks like new. It has been working normally now for over 6 months. Time will tell if there was any other harm done.
If you want to keep it you have to store it.  
Use good quality storage materials!
" Listen to the dude Eric as he knows everything about everything WOW!!! "

is there anything he doesn't know ?
I heard that electrolytic caps degrade faster when not in use?