transtube more likely stands for transistor power-amp , and tube preamp (like Marshall AVT) ... I guess I saw one of those before , it's a Peavy , yeah ?
Power-amp tubes are those which needs to be changed oftenly (that's every couple of years if you gig like daily , or crank it up all the time) ... These are expensive.
Preamp tubes lasts much longer , and can do over 30 years of service ... These are way cheaper than power tubes.
When the tubes are blown you'll certainly notice from the sound & the HUGE loss in volume .