They're both a maintenance nightmare and a danger to poke around in, the cheap stuff from eBay and the super expensive stuff from the fashion designers being the worst.
In all the years I've owned valve gear, I have never had a failure other than a valve and one time SUPER blooper by me. I had a cable drop. That was one
serious screwup. It cost a lot of money. It blew one of 3 dedicated 20 amp circuit. It never blew a fuse in the amp or preamp. The 20 amp breaker.
I've never seen anything like it. The cables from a GG MC275 fell onto a Nord NC500 MB perfectly. + to + and - to negative. I couldn't have made it
do what it did. Of course the amp was brand new. It made a high pitched noise, the right channel Tweeter SMOKED and it blew the main in under 2 seconds.
I sat there for two hours smoking weed as my ears melted off my head, for the total blooper I just pulled.
Within 6 weeks the right channel on the C2500 took a dump. It was the bias circuit on the right main 12AX7. I don't think there would have been a preamp
failure without the cable drop. 13K new. 2K for parts and labor. It blew a transformer in the GG MC275. Very uncommon.
I went and got my 40 year old MB275 plugged it in warmed it up for 2 hours. While waiting I replaced the ribbon in a AC G3s or what ever model they were.
It did nothing to the NC500 MB, NOTHING they were live too. Nord was the Assembler. I have changes brands and went to Cary valve amps. LOL
About the only thing that fails there are the filter caps. LOL They mark their spot like an old Harley (oil on the floor) and blow fuses.
200.00 usd, change the caps in 1 hour, and your up and running.
With the valve units I use it has to be a serious issue for me not to be able to get up and running within 2 hours including repairs.
That includes Herron, Mcintosh, Cary, Decware and a few DIY tube units. Solid State not so much unless its a fuse.
Regards