Better amp or better tubes?


With this lockdown I'm finding myself and I'm sure many others listening to music more often and with that my mind has gone into upgrade mode.
My amp is a rare Quickilver 300B that must be at least 25 years old using genalax gold lion  300b tubes.
Over a year ago I sent an email to Mike sanders asking him about suggesting upgrades to the unit and surprisingly he told me if the amp is working fine to just leave it alone. We ok then.
The genalax 300b are modest in price  costing about $300 a pair and have worked flawlessly. If I were to upgrade the tubes, what direction would you suggest? To be honest, I'm a bit apprehensive in spending a lot for tubes since they can fail at anytime. Am I being overly concerned?

So, do I upgrade the tubes or amp? Amp budget of under 4k.

Thanks


emil
Hello Emil!  If your amp uses a 12AX7 input tube, change it to a New Old Stock Telefunken 12AX7.  I have a 300B tube amp, too and the new input tube made a remarkable. The distributor of my amp (Ele-Kit TU-8600B) says the other tubes don't make enough difference to bother with. At $200 or so, it's not expensive for the big improvement it makes. Keep Smiling.
Thank you all for your input. Much appreciated and something to think about.
@atmasphere 
all tubes have been purchased with the last 2 years with moderate use. I think they should be fine
@decooney 
Upgraditis. Too much free time on my hands. I can easily live with what I have now but isn't this the nature of the hobby?
My system:
Audio Mirror Tubadour III SE
LTA Microzotl Preamp
Quicksilver 300B amps 
Volti Audio modified Khorns
Full Loom Triode Wire Labs cables
@boomerbillone  
Input tubes are 12FQ7 . Recently replaced and purchased from Vintage Tube Services
Rectifier tubes are genelax Gold Lion 5AR4
@Verdantaudio
The Emmision Labs 300B looks like a tube I would be comfortable with considering it's price.

all tubes have been purchased with the last 2 years with moderate use. I think they should be fine
@emil  The age of the tubes and how much use they've had has nothing to do with whether they are good or not. I've bought plenty of bad tubes that were brand new!
@emil
decooney, 
Upgraditis. Too much free time on my hands. I can easily live with what I have now but isn't this the nature of the hobby?

Sure, it can be. Or, until you achieve the title of your post and what is most engaging for you by the way of "better amp" -and- "better tubes" :)