Are all fuses created equal?

My question is not regarding the sonic capabilities of audiophile fuses but is specific to standard fuses and their protective capacity. After all there is the ongoing thread "fuses that matter" that is debating the topic of the sonic capabilities of fuses to death.

The reason for my question is that I recently blew a fuse on my power amp (tube amp). I replaced it with a standard fuse that was rated the same the stock one (2a slow blow). It was purchased from electronics parts distributor. when comparing the new fuse to the stock fuse, I noticed that new one was constructed flimsily. But both were rated the same.

After replacing the fuse while adjusting the bias I shorted one of the output tubes. I immediately shutdown the amp and upon inspection of the fuse it is unclear as to whether it failed (as it should have) or wether it survived the incident. This has prompted me to worry that maybe the fuse had something to do with the shorting of the tube. It is clear to me that the tube in question was nearing the end of its useful life, therefore causing the stock fuse fail in the first place. Regardless, if the tube was faulty the new fuse should have failed as the stock one did.

@Realremo, is changing the fuse type from slo to fast blow wise? I am not convinced, if the circuit was designed with a given fuse type I am not comfortable second guessing the design.

One small side bar regarding the rating of the fuses, engraved on the fuses are the following markings:

stock fuse:
buss
250v
2A
MDL
CSA / UL (logos)

New fuse:
CQ
250v
2A
ADL
CSA / UL (logos)

Does anyone know if these marking have any bearing. Most specifically the MDL vs ADL designations?

thanks

I'm not an electrical engineer, the are much smarter people on this forum than I, but it seems to me that replacing a slo-blow with a fast blo fuse presents less of a risk than vice versa. The fast blo fuse should fail faster than a slo-blo, which would mean less risk of voltage spikes throughout the remainder of the circuit.
I would definitely try to obtain fuses with identical markings tho. I just went to rat-shack and the guy there selected the slow-blows for me, i brought my blown fuse with me and told him I wanted a slow-blow version. I also scoured the internet and found a list of approved fuses deep in the innards of the Rotel site. it was a spreadsheet of fuse types per amp.

as long as it meets rating it's good. the longetivity or built quality may differ.

If they're correct rating and UL listed, they should be.